Athersclerosis & Coronary MRI

                  1230.     Strong Collision Approximation to Predict Iron Volume Fraction in Ex Vivo Atherosclerotic Rabbit’s Aorta

Raimo P. Joensuu¹, Louise M A Anderson, ¹², Anna E. Larsson¹, Li-Ming Gan¹, Malin E. Palmér¹, Paul D. Hockings¹

¹AstraZeneca R&D Molndal, Mölndal, Sweden; ²Chalmers University of Technology, Gothenburg, Sweden

The purpose of this work was to evaluate the suitability of the strong collision approximation to predict the USPIO volume fraction in atherosclerotic rabbits’ vessel wall from the transverse relaxation time, T2*. There was an excellent agreement (R2 = 0.98) between the theory and the measurements for volume fractions larger than 15 ppm. For lower volume fractions the theory agrees with the measurements poorly. The strong collision model may predict correctly the volume fraction from the T2* map when every voxel contains a relatively high number of magnetic particles but fails if the region contains also voxels with few or no particles.

                  1231.     Heparin-Polynitroxide Derivatives: First Application as Site Specific MRT Imaging Contrast Media for Vascular Wall

Maxim V. Terekhov¹, Vasily Sen'², Valery Golubev², Stefan Weber³, Alexander W. Scholz⁴, Thomas Muenzel⁵, Andrei L. Kleschyov⁵, Laura Maria Schreiber³

¹Department of Radiology, Section of Medical Physics,  Johannes Gutenberg University Medical Center Mainz, Mainz, Germany; ²Institute of Problems of Chemical Physics, Russian Academy of Sciences, Russian Federation; ³Department of Radiology, Section of Medical Physics, Johannes Gutenberg University Medical Center Mainz, Mainz, Germany; ⁴Department of Anesthesiology, Johannes Gutenberg University Medical Center Mainz, Mainz, Germany; ⁵II-Department of Medicine, Johannes Gutenberg University Medical Center Mainz, Mainz, Germany

Cyclic nitroxides e.g. TEMPO are stable free radicals with multiple applications in MRI. Heparin is known to have a high affinity for the vascular extracellular structures. We propose that TEMPO could be delivered to the vascular wall by means of heparin-polynitroxide (HNR) derivatives where the nitroxide is linked with the heparin macromolecule. The T1,2 measurements show that HNR complexes provide the relaxivity contrast comparable with Gd-based media. The pilot MRI experiment with ex-vivo labeling of vascular wall with HNR demonstrate high potential of  functionalized polynitroxide targeted to the specific structures of the vascular wall for diagnostic and therapeutic purposes.

                  1232.     Clinical 3.0T Magnetic Resonance Scanner Can Be Used for Imaging of Mouse Atherosclerotic LesionsΦ

Xubin Li^1,2, Huidong Gu¹, Hongqing Feng¹, Xiangke Du², Bensheng Qiu¹, Xiaoming Yang¹

¹Image-Guided Bio-Molecular Intervention Researchers, Department of Radiology; Institute for Stem Cel, University of Washington School of Medicine, Seattle, WA, United States; ²Radiology, Peking University People's Hospital, Beijing, China

The aim of this study was to explore the possibility of generating high-resolution MR images of atherosclerotic aortic walls/plaques of mice using a clinical 3.0 Tesla MR scanner. This study demonstrates that clinical 3.0T MR scanners can be used for high-resolution imaging of atherosclerotic vascular walls and lesions in mice, which is guaranteed with a specific mouse RF coil, an effective ECG-gating system, and a BB-MRI sequence.

                  1233.     Detection of Coronary Artery Wall Inflammation in a Porcine Model Using Non-Contrast Enhanced MRI

Steen Fjord Pedersen¹, William P. Paaske², Troels Thiem³, Samuel A Thrysøe, Erling Falk³, Steffen Ringgaard, Won Yong Kim⁴

¹Dept. of Cardiology, and MR-center, Aarhus University Hospital, Skejby, Aarhus, Denmark; ²Dept. of Cardiothoracic and Vascular Surgery T, Aarhus University Hospital, Skejby; ³Dept. of Cardiology, Aarhus University Hospital, Skejby; ⁴dept. of Cardiology, and MR-center, Aarhus University Hospital, Skejby

Inflammation seems to play a key role in destabilization of atherosclerotic plaques. Detection of Inflammatory activity within atherosclerotic plaques therefore has the potential to distinguish between vulnerable and stable plaques. Using a balloon injured porcine coronary artery, we examined whether edema as a sign of inflammation could be detected in the vessel wall by MRI using a T2-STIR (known to detect edema). After injury, the T2-STIR images showed a significant increase in vessel wall enhancement of 143% (CI95 = [39.6 - 142.5]; and areas with signal enhancement correlated well to inflammation and edema confirmed by histopathology.

                  1234.     Coronary Artery Plaque Imaging: Comparison of Black-Blood MRI and 64-MDCT

Yi He¹, Zhaoqi Zhang¹, Qinyi Dai¹, Wei Yu¹, Biao Lu¹, Zhanming Fan¹, Jing An², Lixin Jin³, Guobin Li⁴, Wolfgang Rehwald⁵, Renate Jerecic³, Debiao Li⁶

¹department of radiology, An zhen hospital, Beijing, China; ²Siemens Mindit Magnetic Resonance, Siemens Healthcare, MR Collaboration NE Asia; ³Siemens Limited China, Siemens Healthcare, MR Collaboration NE Asia; ⁴Siemens Mindit Magnetic Resonance Ltd; ⁵Siemens Healthcare USA; ⁶Northwestern University, Chicago USA

This study was to evaluate the ability of black-blood coronary wall MRI to identify and classify coronary plaques by comparing with 64-MDCT.15 patients underwent black-blood coronary wall MRI and coronary 64-MDCT. In MRI, the plaque burden, maximal wall thickness, SNR, CNR in the coronary walls containing plaques were greater than those of the normal coronary walls.The SNR in the soft plaque was greater than those in calcified and mixed plaques. The conclusion was coronary wall MRI can identify coronary plaques, and has the potential to differentiate plaque types based on signal intensity.

                  1235.     Non-Contrast Coronary Vessel Wall and Plaque Imaging Using Inversion Recovery Prepared Steady State Free Precession: Comparison with Plaque Characterization of 64 Detector Row CT

Takeshi Ishimoto¹, Yasuyo Taniguchi², Tosiaki Miyati³, Momoe Kawakami⁴, Takayuki Ikeda⁵, Hisaya Kusabe⁵

¹Division of Health Science, , Graduate school of Medical, Kanazawa University, Kanazawa, Ishikawa, Japan; ²Department of Cardiology, Hyogo Brain and Heart Center, Himeji, Hyogo, Japan; ³Division of Health Science,, Graduate school of Medical, Kanazawa University, Kanazawa, Ishikawa, Japan; ⁴Radiology and Clinical Laboratory, Hyogo Brain and Heart Center, Himeji , Hyogo, Japan; ⁵Radiology and Clinical Laboratory, Hyogo Brain and Heart Center, Himeji, Hyogo, Japan

In the study, we sought to determine whether coronary vessel wall imaging using inversion recovery prepared SSFP correlate with atherosclerosis detected by 64 raw MDCT. IR-SSFP can be used to non-invasively visualize the coronary vessel wall and to detect the presence of (sub)clinical coronary atherosclerosis . HSI of IR-SSFP may be indicative of plaque inflammation and/or hemorrhage. Therefore, coronary plaque vulnerability could be predicted by cardiac MRI. Further studies are needed to define the importance of these findings in the detection and treatment of vulnerable plaques.

                  1236.     Contrast-Enhanced Whole Heart Coronary MRI with Bolus Infusion of Gadobenate Dimeglumine at 1.5T

Peng Hu¹, Jonathan Chan, Jouke Smink², Beth Goddu, Kraig V. Kissinger, Lois A. Goepfert, Thomas H. Hauser, Neil M. Rofsky³, Warren J. Manning, Reza Nezafat

¹Beth Israel Deaconess Medical Center, Boston, MA, United States; ²Philips Healthcare; ³Radiology, Beth Israel Deaconess Medical Center

We sought to investigate the contrast injection timing and rate for contrast-enhanced coronary artery MRI and compared the images acquired with optimized contrast timing to non-contrast T2-prep whole-heart SSFP coronary MRI at 1.5T. We studied time-resolved blood T1 after gadobenate dimeglumine (Gd-BOPTA) injection using three infusion schemes (bolus, slow infusion and hybrid). Subsequently, we evaluated an isotropic contrast-enhanced whole-heart coronary MRI method at 1.5T using an inversion-recovery SSFP sequence acquired after a bolus infusion of Gd-BOPTA. The contrast-enhanced coronary MRI increased blood SNR by 36% and increased coronary-myocardium CNR by 101%. There was no significant difference in image quality.

                  1237.     3D Flow-Insensitve Coronary Vessel Wall Imaging Using Phase Sensitive Inversion Recovery

Jingsi Xie¹, Himanshu Bhat¹, Zhaoyang Fan¹, Debiao Li¹

¹Departments of Radiology and Biomedical Engineering, Northwestern University, Chicago, IL, United States

Developed a 3D flow-insensitive coronary vessel wall imaging technique.

                  1238.     Contrast-Enhanced Whole-Heart Coronary MRA at 3.0T for the Evaluation of Cardiac Venous Anatomy

Heng Ma¹, Lan Ge², Qi Yang¹, Dong Xu¹, Han Li¹, Qing Tang¹, Jiangtao Liu¹, Wen Qin¹, Jing An³, Lixin Jin⁴, Renate Jerecic⁴, Xiangying Du¹, Kuncheng Li¹, Debiao Li²

¹Xuanwu Hospital, Capital Medical University, Beijing, China; ²Radiology, Northwestern University, Chicago, IL, United States; ³Siemens Mindit Magnetic Resonance Ltd, Shenzhen, China; ⁴Siemens Ltd, Healthcare Sector, China

Fifty-one subjects underwent contrast-enhanced whole-heart coronary magnetic resonance angiography at 3.0T. All major cardiac veins, except for the vein of Marshall, could be depicted successfully.

                  1239.     A New Approach for Single Breath-Hold Whole Heart Coronary MRA Using Highly-Accelerated Parallel Imaging with a 32-Element Coil Array

Jian Xu^1,2, Daniel Kim³, Ricardo Otazo³, Sven Zuehlsdorff⁴, Xiaoming Bi⁴, Bernd Stoeckel¹, Daniel Sodickson³

¹Siemens Medical Solutions USA Inc., New York, NY, United States; ²PolyTechnic Institute of NYU, New York, NY, United States; ³Center for Biomedical Imaging,Department of Radiology, New York University, New York, NY, United States; ⁴Siemens Medical Solutions USA Inc., Chicago, NY, United States

To develop a new approach for high resolution 3D whole heart coronary MRA in a single breath-hold, which offers the potential to enhance imaging efficiency and spatial resolution without apparent misregistration between external RF coil calibration scan and imaging scan.

                  1240.     Whole-Heart Water/Fat Resolved Spiral Imaging for Coronary MRA and Fatty Myocardial Infiltrations

Peter Börnert¹, Kay Nehrke¹, Holger Eggers¹, Peter Koken¹

¹Philips Research  Europe, Hamburg, Germany

Fat suppression is essential to improve contrast in MR coronary angiography (CMRA) but fat also contains helpful diagnostic information. In particular, the intra-myocardial fat represents an important diagnostic indicator that could have high prognostic value. Therefore, in this work whole heart CMRA-type imaging is proposed that delivers both, the coronary tree and the fat signal distribution at the same spatial resolution. Dixon-based chemical shift encoded spiral imaging is used allowing to separate water and fat and to benefits from the ƒ´Bo -based off-resonance correction. This concept was applied and validated in volunteers and shows that efficient CMRA and intra-myocardial fat detection is possible with large volume coverage.

                  1241.     MR-Imaging of the Coronary Arteries of Mice in Vivo

Arno Nauerth¹, Erich Treiber¹, Claudia Oerther¹, Ulrich Flögel²

¹Bruker BioSpin MRI GmbH, Ettlingen, Germany; ²Institut für Herz- und Kreislaufphysiologie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany

In this study the dynamic filling of the coronary arteries in mice was visualized by using a cryogenically cooled surface coil for SNR improvement and by using a  self-gated method with full heart coverage which corrects for cardiac and respiratory motions. The results presents volume-targeted cine-MIPs.

                  1242.     Analysis of Small Dilation Detection in Coronary Angiography

Travis B. Smith¹, Krishna S. Nayak¹

¹Electrical Engineering, University of Southern California, Los Angeles, CA, United States

Estimation of coronary artery cross-sectional lumen area from MR images is now being used to assess the relationship between atherosclerosis and vasomotion response to endothelial-dependent stimuli. Typically, cross-sectional images of the coronary lumen acquired before and after administration of such stimuli are fit to circular templates to estimate the change in area. These studies have reported very small mean changes in lumen area. In this work, we develop a statistical framework for the detection of these subtle changes in lumen area using two images.  We use this framework to relate detection performance to SNR requirements and minimum detectable dilation.

                  1243.     Analysis of Coronary Vein Motion: Implications for MR Coronary Vein Venography

Pierre John Watson¹, Jonathan D. Suever², John N. Oshinski¹

¹Radiology, Emory University, Atlanta, GA, United States; ²Biomedical Engineering, Georgia Institute of Technology

The periods of low motion of the coronary veins during the cardiac cycle were quantified using 3D magnetic resonance coronary venograms (cMRV) in 16 patients with ischemic heart disease.  The temporal location and duration of these periods were determined using the frame-to-frame displacement method on the coronary sinus.  The patients were classified as either systolic or diastolic dominant based on the duration of the periods.  The majority of patients were systolic dominant although about a third of the patients either had a very short diastolic period or lacked it completely.

                  1244.     Motion Correction Coeeficient Pre-Analysys Method for Whole-Heart Magnetic Resonance Coronary Angiography (Wh Mrca) for Use in a Clinical Setting

Yuki Ohmoto¹, Rieko Ishimura², Takashi Yoshida³, Miho Yabuyamada³, Junji Takahashi³, Shigehide Kuhara⁴, Sachiko Isono⁴, Ayako Ninomiya⁴, Mitsue Miyazaki⁴, Hiroyuki Tsuji¹, Yasuji Arase¹

¹Health Management Center, Toranomon Hospital, Minato-ku, Tokyo, Japan; ²Cardiovascular Center, Toranomon Hospital; ³Radiology, Toranomon Hospital; ⁴MRI systems Division, Toshiba Medical Systems Corporation

Whole-Heart Magnetic Resonance Coronary Angiography (WH MRCA) is a very useful tool for screening for coronary artery disease and usually performed during free breathing with real time motion correction (RMC). We have developed a Motion Correction Coefficient Pre-Analysis Method to obtain an appropriate RMC coefficient before the WH MRCA scan and performed the feasibility study of this method by evaluating the relation between the coefficient of RMC and the image quality for health screening cases retrospectively. The results showed that this method is expected to be very useful in the clinical application of WH MRCA.

                  1245.     Global-To-Local Tandem Method for Detecting the Coronary Stationary Period for Whole-Heart Magnetic Resonance Coronary Angiography (Wh Mrca)

Ayako Ninomiya¹, Shigehide Kuhara¹, Tomohisa Okada², Tetsuo Sato³, Kotaro Minato³, Shoutaro Kanao², Kaori Togashi²

¹MRI Systems Division, Toshiba Medical Systems Corporation, Otawara-shi, Tochigi, Japan; ²Kyoto University Hospital, Kyoto, Japan; ³Nara Institute of Science and Technology, Nara, Japan

We have developed the Global-to-Local Tandem Method to detect the coronary stationary period for WH MRCA, in which the coronary stationary period is roughly analyzed by the global method and then more precisely analyzed by the local method. We have also conducted clinical feasibility studies. Results suggest that The Global-to-Local Tandem Method can robustly detect the coronary artery stationary period in WH MRCA (Whole Heart Magnetic Resonance Coronary Angiography). It is therefore concluded that this method should prove to be very useful for clinical WH MRCA examinations.

                  1246.     Retrospective Motion-Adapted Smart Averaging for Free-Breathing Cardiac MRI

Alan Christopher O'Connor^1,2, Mehdi Hedjazi Moghari¹, Peng Hu¹, Dana C. Peters¹, Warren J. Manning¹, Reza Nezafat¹, Roger Ware Brockett²

¹Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States; ²SEAS, Harvard University, Cambridge, MA, United States

Navigator gating is an accepted method for reducing the effect of respiratory motion in cardiac MRI; however, it does not exploit the fact that different spatial frequencies are more or less sensitive to the respiratory motion.  We present a smart motion-adapted averaging method that retrospectively corrects for respiratory motion by combining data from k-space lines of multiple acquisitions using weights determined by the navigator signal.

                  1247.     CoSMo:  Compressed Sensing Motion Correction for Coronary MRI

Mehdi Hedjazi Moghari *¹, Mehmet Akçakaya *,¹², Alan O'Connor, ¹², Peng Hu¹, Vahid Tarokh², Warren J. Manning¹, Reza Nezafat¹

¹Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, United States; ²Harvard University, Cambridge, MA, United States

We examine the feasibility of using compressed sensing to reduce artifacts due to respiratory motion. Respiratory motion causes image artifacts and ghosting in cardiac imaging. Respiratory navigators are one of the methods used to mitigate these artifacts for free-breathing scans, where k-space lines falling outside a pre-defined gating window are reacquired until the whole k-space is filled. In this study, we introduce CoSMo, a compressed sensing-based method for reconstructing images without having to reacquire k-space lines rejected by the navigator.

                  1248.     New Approach for Patient-Specific Estimation of Cardiac Motion Due to Respiration

Florencio Rusty Baldomaro Punzalan¹, Tetsuo Sato¹, Tomohisa Okada², Shigehide Kuhara³, Kaori Togashi², Kotaro Minato¹

¹Graduate School of Information Science, Nara Institute of Science and Technology, Ikoma, Nara, Japan; ²Department of Diagnostic Radiology, Kyoto University Hospital, Kyoto, Japan; ³MRI Systems Division, Toshiba Medical Systems, Tochigi, Japan

Respiratory motion compensation for cardiac imaging requires a patient-specific knowledge of the heart’s motion. In this study, the respiratory-induced motion of the upper and lower part of the heart was investigated during free-breathing. We observed significant inter-subject variation of upper and lower heart motion tracking factors. The tracking factor for the lower part is larger than the upper part for all subjects. This will help motion models account for the different displacements and velocities of coronary vessels located in the atrio-ventricular groove (RCA and LCX) and the apex (LAD) which are located in the lower and upper heart, respectively.

                  1249.     Which Factors Influence MRI In-Stent Lumenvisibility of Coronary In-Stent Stenosis? an In-Vitro Model Investigation

Gerrit Schönwald¹, Gregor Schaefers², Georg Haltern³, Brigitte Kipfmüller⁴

¹University Witten/Herdecke, Gelsenkirchen, NRW, Germany; ²MR:comp GmbH, Gelsenkirchen, Germany; ³HELIOS Heart Center , Wuppertal, Germany; ⁴University of applied Science Gelsenkirchen, Germany

Purpose Development of a standardized procedure to evaluate which factors need to be optimized for quantification of in-stent stenosis by analysis of lumenvisibility in a static MRI model of coronary in-stent stenosis. Methods Stents were placed into tubes and equipped with artificial restenosis made of a pre-investigated material. The tubes were placed in a phantom. A 1.5 and a 3 Tesla MR-system were used. Results Quantification of in-stent stenosis was limited in stainless steel stents and cobalt-chromium stents by artifacts. Tantalum stent showed a lower rate of artifacts. Conclusion Image quality was strongly depended from stent material and stent design.

Vessel Wall Imaging (Non-Coronary)

                  1250.     Comparison Between Ungated Multi-Slice and Gated Single-Slice Double Inversion Recovery Prepared Black-Blood Fast Spin Echo Sequences Applied at 3T

Andrew J. Patterson¹, Victoria E. Young¹, Martin J. Graves¹, Jonathan H. Gillard¹

¹Radiology, University of Cambridge, Cambridge, England, United Kingdom

Double inversion recovery prepared, fast spin echo, black blood imaging has been widely used for assessing carotid plaque tissue composition. The protocol is used to obtain T₁-, T₂- and PD-weighted contrast. This study compares the between subject and within subject differences in the signal-to-noise ratio and the contrast-to-noise ratio from single- and multi-slice acquisition using both a gated and ungated trigger.

                  1251.     Black Blood Imaging of Carotid Plaque Using Spatial Labeling with Multiple Inversion Pulses Prepared Spoiled Gradient Recalled Sequence

Hao Shen¹, Guang Cao², QingJun Wang³

¹Applied Science Laboratory, GE Healthcare, Beijing, China; ²Applied Science Laboratory, GE Healthcare, Hong Kong, China; ³Department of Radiology, Chinese PLA General Hospital, Beijing, China

Black blood is important in carotid plaque characterization. In this study, we developed a black blood spoiled gradient recalled sequence by using spacial labeling with multiple inversion pulses preparation.

                  1252.     High Resolution 3D Black Blood Carotid Artery Imaging Using 3D TSE Sequence with Non-Selective Refocusing RF and Inner Volume Imaging Technique.

Seong-Eun Kim^1,2, Scott McNally², Laura K. Findeiss², Jordan Hulet³, John Roberts^1,2, Eun-Kee Jeong^1,2, Dennis L. Parker^1,2, Gerald S. Treiman^4,5

¹UCAIR, University of Utah, Salt Lake City, UT, United States; ²Department of Radiology, University of Utah, Salt Lake City, UT, United States; ³Department of Biomedical Informatics, University of Utah; ⁴Department of Surgery, University of Utah, Salt Lake City, UT, United States; ⁵Veterans Affair, VASLCHCS, Salt Lake City, UT, United States

2D TSE with DIR is the current technique for identification of the component of carotid plaque. This approach is limited by inadequate spatial resolution that is often necessary to identify small areas of plaque components. 3D imaging offers the potential to improve spatial resolution. We have utilized 3D TSE with non-selective 180o RF and have implemented an inner volume imaging(IVI) technique. The non-selective 180o RF allow significantly more echoes to be acquired resulting in more efficient 3D scan. IVI technique reduces the field of view in the phase encoding direction and requires fewer phase encoding line, further reducing scan time.

                  1253.     Intravascular 3.0T MR Imaging: A Feasibility Study in Swine

Yanfeng Meng^1,2, Feng Zhang¹, Huidong Gu¹, Jinnan Wang³, Chun Yuan¹, Zhaoqi Zhang², Bensheng Qiu¹, Xiaoming Yang¹

¹Radiology, University of Washington, Seattle, WA, United States; ²Radiology, Beijing Anzhen Hospital, Beijing, China; ³Clinical Sites Research Program, Philips Research North America, Briarcliff Manor, NY, United States

This study was to validate the feasibility of generating intravascular 3T MRI of deep-seated arteries of near-human-sized swine by using a 3T-MR compatible MR-imaging guidewire (MRIG). For in vitro testing, we compared SNRs generated by a 0.032-inch MRIG and surface coils. For in vivo validation, we performed intravenous MRI of the parallel-run iliofemoral arteries with this MRIG. The SNR by the MRIG was higher than surface coils, and the iliofemoral arterial walls were clearly delineated with the MRIG at a higher SNR than surface coils. This study establishes the groundwork for further intravascular 3T MRI of deep-seated arteries in humans.

                  1254.     Histology Assisted Validation of Automatic Detection of Soft Plaque in Vessel Wall Images by Using Optimal Number of MR Sequences

Ronald van 't Klooster¹, Andrew J. Patterson², Victoria E. Young², Jonathan H. Gillard², Johan H.C. Reiber¹, Rob J. van der Geest¹

¹Division of Image Processing, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands; ²University Department of Radiology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom

Extensive MR vessel wall imaging protocols are used to identify unstable plaques, which play an important role in the progression of atherosclerosis. Comparison was made between automatic plaque detection, by a supervised classification system, and histology assisted manual segmentation. Experiments show that the automatic detection of unstable plaque is in good agreement with the manual segmentation. Moreover, the STIR and DWI sequences show an improvement over the T2w and PDw sequences. Automatic detection of soft plaque may be feasible by using a limited number of MR sequences, saving both MRI system and image analysis time.

                  1255.     Improved Calcification Detection Accuracy on Human Atherosclerotic Plaque Using Ultra-Short TE (UTE) Imaging

Jinnan Wang¹, Marina S. Ferguson², Niranjan Balu², Chun Yuan², Peter Boernert³

¹Clinical Sites Research Program, Philips Research North America, Seattle, WA, United States; ²University of Washington; ³Philips Research Europe

Ultra-short TE (UTE) images can provide positive contrast for short T2 species when combined with imaging techniques like dual-echo subtraction or magnetization preparation. Although the calcified regions identified on UTE images were demonstrated to agree with CT images, its accuracy has not been validated against histology. This study is aimed at comparing the accuracy of UTE calcification detection in human carotid plaques against regular turbo spin echo MR images, as well as validating it against histology.

                  1256.     Response of the Carotid Vessel Wall to Lipid-Lowering Therapy: Time Course of T1 and T2-Weighted Signal Variation

Li Dong¹, William Sean Kerwin¹, Chun Yuan¹, Xue-Qiao Zhao¹

¹University of Washington, Seattle, WA, United States

We hypothesized that lipid-lowering therapy leads to biological changes in arterial walls that result in altered MRI contrast, even in the absence of a developed necrotic core. In a carotid MRI study of atorvastatin, 42 subjects exhibited no necrotic core. Within this group, no measurable change in wall thickness occurred over 3 years, but a highly significant (p<0.001) change in T2-weighted versus T1-weighted signal intensity was observed. Therefore, signal changes in the vessel wall may be more sensitive than plaque burden for measuring treatment effects in early lesions of atherosclerosis.

                  1257.     MR Elastography of the In Vivo Abdominal Aorta:  Feasibility Study

Arunark Kolipaka¹, David A. Woodrum¹, Krzysztof R. Gorny¹, Oscar I. Garcia Medina¹, Anthony J. Romano², Richard L. Ehman¹

¹Radiology, Mayo Clinic, Rochester, MN, United States; ²Acoustics Division, Naval Research Laboratory, Washington DC, United States

To date there is no noninvasive method to reliably estimate the stiffness of the abdominal aorta. We are investigating MR elastography to estimate the stiffness of in vivo abdominal aorta in normals and controlled hypertensive volunteer. Our preliminary results suggest that discernible waves are observed in the abdominal aorta, and controlled hypertensive volunteer has shown higher stiffness measurement when compared to normal volunteers. Therefore, MRE technique is feasible and can be used to examine the stiffness of the abdominal aorta.

                  1258.     VCAM-1 Targeted MRI for Imaging of Inflammation in Mouse Atherosclerosis Using Paramagnetic and Superparamagnetic Lipid-Based Contrast Agents

Glenda Sibylle van Bochove¹, Martijn L. Chatrou¹, Leonie E. Paulis¹, Holger Grüll^1,2, Gustav J. Strijkers¹, Klaas Nicolay¹

¹Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands; ²Bio-Molecular Engineering, Philips Research Europe, Eindhoven, Netherlands

The purpose of this study was to image VCAM-1 expression in carotid artery lesions of apoE-/- mice, to compare the efficacy of a lipid-based paramagnetic and a lipid-based superparamagnetic contrast agent, and to relate contrast changes to plaque location. Paramagnetic liposomes and superparamagnetic micellar iron oxides targeted to VCAM-1 were prepared. Both contrast agents showed strong and specific accumulation in VCAM-1 over-expressing cells in vitro. In vivo targeting to mouse carotid artery atherosclerotic plaques was demonstrated. Contrast changes were most pronounced in the plaque shoulders, which are known to be most active in inflammatory cell recruitment.

                  1259.     Association Between Carotid Artery and Thoracic Aorta Plaque Burden in Patients with Neurovascular Symptoms: A 3.0T, Multiple Vascular Beds, Black-Blood Vessel Wall Imaging Study

Xihai Zhao¹, Huilin Zhao², Ye Cao², Jinnan Wang³, Niranjan Balu¹, Jianrong Xu², Chuan Yuan¹

¹Radiology, University of Washington, Seattle, WA, United States; ²Radiology, Shanghai Renji hospital, Shanghai Jiaotong University, Shanghai, China; ³3. Philips Research North America, Briarcliff Manor, NY, United States

Atherosclerosis is a systemic disease frequently involving multiple vascular territories, such as carotid artery and thoracic aorta, which are related to cerebrovascular events. Thus, atherosclerotic disease in one vascular bed may be an indicator for the other vasculatures. This study sought to determine the association between carotid artery and thoracic aorta atherosclerosis using MR black-blood vessel wall imaging in 26 symptomatic patients. We found that carotid artery plaque burden, particularly on left side, was significantly associated with that of descending aorta. Our findings suggest that atherosclerotic disease in carotid artery may be an indicator of thoracic atheroma, or vice versa.

                  1260.     Accelerating 3D Molecular MR Imaging Using Compressed Sensing

Claudia Prieto¹, Marcelo Andia¹, Tobias Schaeffter¹, Rene M. Botnar¹

¹Division of Imaging Sciences, King's College London, London, United Kingdom

Accelerated Molecular MR-imaging using Compressed Sensing (CS) is demonstrated for preclinical applications. The sparsity requirement of CS is satisfied in most molecular MR-images, due to the high localized T1-contrast enhancement produced by target-specific contrast agents. Good overall image quality was achieved with acceleration factors up to 4 in 3D preclinical studies of venous thromboembolism and aortic vessel wall. CS is especially useful for small animal studies (requiring high spatial resolution and thus suffering from prolonged scan times), whereas other acceleration techniques such as parallel imaging often cannot be applied due to the limited availability of multi channel small animal coils.

                  1261.     Anti-Angiotensin Drug Evaluation in ApoE-/- Mice by USPIO-Enhanced MRI at 7T

Olivia Monica Sigovan¹, Amine Bessaad¹, Elena Kaye², Eric Lancelot³, Claire Corot³, Nicolas Provost⁴, Zouher Majd⁴, Magali Breisse⁴, Emmanuelle Canet-Soulas¹

¹CREATIS-LRMN Laboratory, Lyon1 University, Lyon, France; ²Radiology, Stanford University, United States; ³Guerbet Group, Paris, France; ⁴Genfit, Lille, France

Irbesartan (SR 47436) is an orally active nonpeptide Angiotensin II type 1 (AT1) receptor antagonist. We report here an USPIO-enhanced MRI follow-up study performed on apolipoprotein (apo) E-deficient mice with the goal of following Irbesartan’s therapeutic effect on the development and progression of atherosclerotic lesions. Irbesartan lead to a marked reduction in the plaque formation. Post USPIO T2* values measured in the vessel wall showed significant decrease compared to baseline values, however no differences were found between treated and not treated groups. The obtained information (from the ascending aorta) may not be representative of the general effect of the drug.

                  1262.     DCE-MRI for the Evaluation of Atherosclerosis in Patients with Exposure to Particulate Matter

Venkatesh Mani¹, Simonette T. Sawit², Claudia Calcagno¹, Cynara Maceda², Colin Moncrieff¹, Zahi Adel Fayad¹, Jacqueline Moline³, MaryAnn McLaughlin²

¹Radiology, Mount Sinai School of Medicine, New York, NY, United States; ²Cardiology, Mount Sinai School of Medicine, New York, NY, United States; ³Preventive Medicine, Mount Sinai School of Medicine, New York, NY, United States

Exposure to particulate matter (PM) has been associated with adverse health effects leading to increased morbidity and mortality. Dynamic contrast enhanced (DCE) MRI and peripheral arterial tonometry (PAT) may potentially be used to evaluate differences in atherosclerosis in patients with high and low PM exposure. There was correlation between DCE-MRI measures and endothelial function measured by PAT. Despite NO significant differences between groups in patient characteristics, and vessel wall morphometrics, high exposure group had significantly lower DCE MRI measures.  We conclude that DCE-MRI may be used to evaluate differences in atherosclerosis due to different levels of PM exposure.

                  1263.     In Vivo Carotid Plaque Magnetic Resonance Imaging Using Quantitative T₂* Measurments with USPIO Particles: A Dose-Response Study to Statin Therapy

Andrew James Patterson¹, Tjun Y. Tang¹, Martin J. Graves¹, Simon P. S. Howarth¹, Jonathan H. Gillard¹

¹Radiology, University of Cambridge, Cambridge, England, United Kingdom

Previous studies have reported Ultra-Small Super-Paramagnetic Iron Oxide (USPIO) detected inflammation in carotid atherosclerotic disease using a semi-quantitative analysis technique that involves measuring changes in signal intensity relative to adjacent muscle tissue. In this study an alternative method to detect and quantify changes over-time is presented. The methodology involved making direct quantitative T₂* measurements within the atherosclerotic plaque pre- and post- infusion. In a double blinded randomised control trail this study measured a significant difference (p<0.001) with respect to time in USPIO-detected inflammation between patients receiving low-dose and high-dose statin therapy.

                  1264.     Symptomatic Patients with Mild to Moderate Carotid Stenosis: Plaque Features at MRI and Association with Cardiovascular Risk Factors and Statin Use

Robert Kwee¹, Robert van Oostenbrugge, Martin Prins, Jos van Engelshoven, Joachim Wildberger, Werner Mess, Eline Kooi

¹Maastricht University Medical Center, Maastricht, Limburg, Netherlands

We found that TIA/stroke patients with moderate carotid stenosis have a higher prevalence of complicated plaques at MRI compared to TIA/stroke patients with mild stenosis. Increasing age is positively associated with the presence of IPH, while the use of statins is negatively associated with complicated plaque features. Other major cardiovascular risk factors were not associated with plaque composition, suggesting that assessment of plaque composition provides independent information, which might be used to improve risk-stratification for stroke.

                  1265.     Assessment of Inflammation in a Rabbit Model of Early Atherosclerosis: Reproducibility and Accuracy of Kinetic Analysis Approaches with Black-Blood DCE-MRI

Huijun Chen¹, Jinhui Shen¹, William S. Kerwin¹

¹Department of Radiology, University of Washington, Seattle, WA, United States

DCE-MRI has been shown to be sensitive to inflammatory content within plaque. Previous bright-blood technique is not compatible with early lesions due to the enhancement contamination from lumen. Recently, the area under enhancement curve (AUC) has been found to be associated with neovessels in early atherosclerosis by black-blood imaging. In this study, we demonstrated the potential for kinetic modeling of black blood DCE-MRI of atherosclerotic plaque using a reference region approach to the Patlak model. Using an animal model of early atherosclerosis, both kinetic parameters exhibited better reproducibility and stronger correlation with inflammatory bio-markers than the AUC ratio.

                  1266.     MRI Detects Oxidative Stress Induced by Methaemoglobin

General Leung¹, Alan R. Moody¹

¹Medical Imaging, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada

Carotid plaque haemorrhage detected by magnetic resonance imaging appears to be prognostic regarding plaque progression and patient outcome. It is accepted that oxidative modification of low density lipoprotein (LDL) first causes then drives plaque development. We demonstrate in vitro that the signal hyperintensity caused by ferric haemoglobin, a major portion of intraplaque haemorrhage detected by MRI, is associated with an environment that is a potent oxidiser of LDL.

                  1267.     Comparison of Black-Blood Magneization Preparation Techniques for 3D Vessel Wall Imaging in the Lower Extremities

Keigo Kawaji^1,2, Thanh D. Nguyen², Beatriu Reig², Pascal Spincemaille², Martin R. Prince², Yi Wang^1,2

¹Biomedical Engineering, Cornell University, Ithaca, NY, United States; ²Radiology, Weill Cornell Medical College, New York, NY, United States

This work compared the performance of four black-blood magnetization preparation techniques [double inversion recovery (DIR), spatial presaturation of upstream blood (SpSat), motion-sensitizing magnetization preparation (MSprep), and T2prep inversion recovery (T2prep-IR)] in suppressing blood signal in a 3D balanced steady-state free precession MRA of the lower extremity.  In 11 volunteers, the proximal popliteal was imaged at 1.5-Tesla with the four magnetization preparation techniques.   Both MSprep and T2prep-IR provided global blood suppression and vessel wall visualization across a 3D volume, while upstream blood nulled by DIR and SpSat did not travel across the entire 3D volume.

                  1268.     Ruptured Carotid Plaques as a Feature in Patients with Unstable Angina Pectoris

Jianming Cai¹, Qingjun Wang¹, Yong Wang¹, Youquan Cai¹, Lin Ma¹, Dongxiang Xu², Chun Yuan²

¹Radiology, Chinese PLA General Hospital, Beijing, China; ²Radiology, University of Washington, Seattle, WA, United States

By using multi-contrast high-resolution MRI, we studied prospectively whether carotid plaque characteristics can predict unstable angina pectoris (UAP). In the present study, each subject with stenosis >50% in one or more major coronary arteries was performed a carotid MRI examination on a 3.0-T MRI scanner. Our findings show that the presence of fibrous cap rupture was the strongest independent predictor of UAP. With a multi-contrast high-resolution MRI, the ruptured carotid plaques may be a surrogate marker for identifying patients at high risk of UAP and may contribute to a better risk stratification of patients with coronary artery disease.

                  1269.     Intracranial Vessel Wall Imaging at 7 Tesla

Jaco J.M. Zwanenburg¹, Anja G. van der Kolk¹, Jeroen Hendrikse¹, Peter R. Luijten¹

¹Radiology, University Medical Center Utrecht, Utrecht, Netherlands

A volumetric (3D) turbo spin echo (TSE) sequence for intracranial vessel wall imaging at 7 Tesla is presented. Images show the vessel walls of the circle of Willis, and of the ophtalmica.

                  1270.     Measurement of the Mean ADC Values of Lipid, Hemorrhage and Overall Wall Components Using In-Vivo Human Carotid Artery Diffusion Weighted Imaging

Seong-Eun Kim^1,2, Scott McNally², Laura K. Findeiss², Jordan Hulet³, John Roberts^1,2, Eun-Kee Jeong^1,2, Dennis L. Parker^1,2, Gerald S. Treiman^4,5

¹UCAIR, University of Utah, Salt Lake City, UT, United States; ²Department of Radiology, University of Utah, Salt Lake City, UT, United States; ³Department of Biomedical Informatics, University of Utah; ⁴Department of Surgery, University of Utah, Salt Lake City, UT, United States; ⁵Veterans Affair, VASLCHCS, Salt Lake City, UT, United States

Atherosclerotic plaques are composed of varying degrees of lipid, necrotic tissue, loose connective tissue, hemorrhage, and calcification.  The extent of lipid accumulation and the presence of intramural hemorrhage have been found to be associated with the degree of plaque vulnerability and risk of plaque rupture. Recent ex vivo studies of carotid plaques found that DWI could detect lipids and hemorrhage with greater sensitivity than other MRI.  This study reports the ADC values of lipid, hemorrhage and overall wall composition as measured with in-vivo DWI, with histology used as the basis for comparison

                  1271.     High Resolution 3D Carotid Plaque Perfusion Mapping and Its Association with T2 Hyperintensity

Michael Jerosch-Herold¹, YiuCho Chung², Ravi Teja Seethamraju³, Otavio R. Coelho-Filho⁴, Marcelo Fernando Di Carli, Peter Libby, Raymond Y. Kwong

¹Radiology, Brigham & Women's Hospital, Boston, MA, United States; ²MRI, Siemens Medical Systems, Columbus, OH, United States; ³Siemens Medical Systems, Boston, MA, United States; ⁴Brigham & Women's Hospital, United States

The transfer rate (Ktrans) of gadolinium contrast into the extracellular space is a validated marker of carotid plaque neo-vascularization and inflammation. T2-weighted imaging is a complementary marker of inflammation in vessel wall and plaque. The association between Ktrans and increased SI on T2 images of carotid plaque was investigated in this study by high resolution, 3D dynamic T1w gradient echo imaging, and a 3D T2w TSE method (T2-SPACE). Ktrans and T2-signal hyper-enhancement were found to be strongly associated markers of neo-vascularization and inflammation, respectively.

                  1272.     In Vivo Characterization of a New Abdominal Aortic Aneurysm Mouse Model with Conventional and Molecular MRI

Ahmed Klink¹, Joeri Heynens², Beatriz Herranz³, Hendrik M. Sanders², Gustav J. Strijkers², Klaas Nicolay², Maarten Merkx, Ziad Mallat⁴, Willem J.M. Mulder¹, Zahi A. Fayad¹

¹Translational and Molecular Imaging Institute, Mount Sinai School of Medicine, New York, NY, United States; ²Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands; ³Vascular Imaging and Atherothrombosis, CNIC, Madrid, Spain; ⁴Paris Cardiovascular Research Center, INSERM, U689, Paris, France

The in vivo characterization of a novel mouse model of abdominal aortic aneurysm (AAA) was achieved with both multi-contrast MRI (PDW, T2W, T1W, TOF) and collagen-targeted MR molecular imaging. The latter was performed with fluorescent/paramagnetic micelles conjugated to the collagen-specific protein CNA35. This allowed the imaging of the collagen turnover believed to be key in AAA progression and rupture. We established that these MRI tools were very valuable for the longitudinal investigation of AAA progression in this mouse model of AAA.

                  1273.     Carotid Artery Wall Lipid Quantification by Means of 1H-Magnetic Resonance Spectroscopy:  Correlation with Carotid Wall Area and Normalized Wall Index.

Raphael Duivenvoorden¹, Adriaan G. Holleboom¹, Eric de Groot¹, Dirkjan F. Enklaar¹, Johan S. Laméris², John J.P. Kastelein¹, Erik S.G. Stroes¹, Aart J. Nederveen²

¹Vascular Medicine, Academic Medical Center, Amsterdam, NH, Netherlands; ²Radiology, Academic Medical Center, Amsterdam, NH, Netherlands

We developed a carotid MRS protocol to non-invasively test the relation between the lipid to water ratio at the location of the carotid artery wall and carotid artery wall dimensions. We found that the lipid:water ratio correlated with the carotid artery wall dimensions, independent of serum lipid levels. Further research is needed to resolve whether MRS is a useful tool to assess the efficacy of lipid altering pharmacotherapy in the treatment of advanced atherosclerotic lesions.

                  1274.     Efficient Flow Suppressed MRI Improves Reproducibility of Carotid Atherosclerosis Plaque Burden Measurements

Li Dong¹, Jinnan Wang², Vasily Yarnykh¹, Hunter Underhill¹, Moni Neradilek³, Thomas Hatsukami¹, Chun Yuan¹

¹University of Washington, Seattle, WA, United States; ²Philips Research North America; ³The Mountain-Whisper-Light Statistics

Previous studies found that a turbo spin-echo based motion-sensitized driven-equilibrium (MSDE) sequence, provides more efficient residual flow signal suppression than the widely used multislice double inversion recovery (mDIR). However, whether this improved flow-suppression can improve reproducibility in atherosclerotic burden measurement is unknown. Bilateral carotid arteries (n=36) from 18 asymptomatic subjects underwent two carotid MRI examinations within 12 days. Compared to mDIR, the MSDE technique had a significantly reduced inter-scan reproducibility for lumen and wall area. For future clinical trials using carotid MRI, improved flow suppression techniques is recommended to monitor progression or regression of atherosclerosis plaque burden.

                  1275.     Femoral Artery Vessel Wall Imaging Using Contrast-Enhanced, Susceptibility Weighted Imaging

Qi Liu¹, Zhaoyang Fan¹, Qi Yang², E Mark Haacke³, Debiao Li¹

¹Departments of Radiology and Biomedical Engineering, Northwestern University, Chicago, IL, United States; ²Xuanwu Hospital, Beijing, China; ³Department of Biomedical Engineering, Wayne State University, Detroit, MI, United States

By using a gradient-echo sequence with a relatively long echo time with flow compensation, together with proper post processing to preserve tissue susceptibility property while removing unwanted phase aliasing, arterial wall delineation was achieved in SWI phase images. To further enhance the lumen-wall contrast in phase images, we hypothesized that by injecting contrast agent which is known to alter blood susceptibility, more pronounced lumen-wall contrast could be obtained. Our contrast-enhanced SWI study on volunteers has confirmed the above hypothesis and observed substantial increase in lumen-wall phase contrast.

                  1276.     Zoom Imaging for Cardiovascular Risk Assessment

Tarique Hussain¹, Rachel Clough¹, Gerald Greil¹, Rene Botnar¹

¹Division of Imaging Sciences, King's College London, London, United Kingdom

In this study we applied the restricted field-of-view (FOV) zoom imaging technique for the reduction of scan time in diagnostic turbo-spin-echo (TSE) black blood aortic vessel wall imaging. Images were compared to a full FOV vessel wall acquisition and image quality was assessed.

                  1277.     Serial Contrast-Enhanced Vessel Wall MRI in a Model of Plaque Neovascularization

Stephanie Elaine Chiu¹, General Leung¹, James Q. Zhan², Alan R. Moody, ¹²

¹Medical Biophysics, University of Toronto, Toronto, Ontario, Canada; ²Medical Imaging, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada

This study introduces a measure extracted from gadofosveset-enhanced MR images of advanced rabbit atherosclerotic plaques for the study of plaque neovascularization.  Animals were scanned 1 week before, 5 weeks after, and 10 weeks after endothelial denudation of the abdominal aorta.  Vessel wall enhancement area measured from post-contrast MR images obtained prior to sacrifice was strongly associated with histologically-measured microvessel count, intimal area, and macrophage area.  Vessel wall enhancement area also monitored plaque development in the same group of animals over time.  This MR measure is suitable for the longitudinal study of changes in plaque neovascularization and inflammation.

                  1278.     Magnetic Resonance Imaging of Inflammation in Abdominal Aortic Aneurysms Using USPIO

Jennifer Margaret Jane Richards¹, Scott I. Semple², Calum Gray², William Wallace³, Roderick TA Chalmers⁴, Olivier James Garden⁵, Graham McKillop⁶, David E. Newby¹

¹Centre of Cardiovascular Science, University of Edinburgh, Edinburgh, United Kingdom; ²Clinical Research Imaging Centre, University of Edinburgh, Edinburgh, United Kingdom; ³Department of Pathology, NHS Lothian, Edinburgh, United Kingdom; ⁴Vascular Surgical Service, NHS Lothian, Edinburgh, United Kingdom; ⁵Clinical and Surgical Sciences (Surgery), University of Edinburgh, Edinburgh, United Kingdom; ⁶Department of Radiology, NHS Lothian, Edinburgh, United Kingdom

The ability to evaluate the biological processes affecting the vessel wall in abdominal aortic aneurysms (AAA) would be beneficial in addition to vessel diameter when evaluating the risk of aneurysm rupture. This is a clinical study (n=9) of the use of Magnetic Resonance Imaging and  ultrasmall superparamagnetic particles of iron oxide (USPIO, Sinerem, Guerbet) to detect focal areas of inflammation in the wall of AAA. A reduction in T2* value was observed on T2* weighted imaging before and 24hrs after intravenous administration of 2.6mg/kg Sinerem. Histological examination of operative tissue samples confirmed the presence of iron in the aortic wall.

                  1279.     Preliminary Evaluation of the Short Term Reproducibility of Dynamic Contrast Enhanced (DCE) MRI in Patients with Carotid Atherosclerosis

Claudia Calcagno¹, Venkatesh Mani¹, Sarayu Ramachandran¹, Silvia Aguiar¹, John Postley², Zahi A. Fayad¹

¹Radiology, Mount Sinai School of Medicine, New York, NY, United States; ²Columbia University - College of Physicians and Surgeons

Dynamic contrast enhanced (DCE) MRI can quantify plaque inflammation in atherosclerosis, however its reproducibility is still unknown. We present a preliminary study of the inter-scan reproducibility of the area under the curve (AUC) of contrast agent uptake calculated from DCE-MRI acquisitions in patients with carotid atherosclerosis. We show excellent reproducibility of plaque AUC relative to ipsi-lateral sternocleidomastoideal muscle AUC (ICC respectively 0.972 and 0.755, p<0.05). This preliminary study show encouraging results and suggests that DCE-MRI could be a useful tool for the clinical evaluation of human atherosclerosis and/or in longitudinal clinical drug trials.

                  1280.     Syrian Hamster Model of Postmenopausal Hypercholesterolemia Atherosclerosis and the Development of Plaques as Imaged by High Field MRI

Jens T. Rosenberg^1,2, Sara Campbell³, Ihssan Masad, ¹², Bahram H. Arjmandi³, Samuel Colles Grant, ¹²

¹CIMAR, The National High Magnetic Field Laboratory, Tallahassee, FL, United States; ²Chemical and Biomedical Engineering, The Florida State University, Tallahassee, FL, United States; ³Nutrition, Food and Exercise Sciences, The Florida State University, Tallahassee, FL, United States

Ovariectomized (ovx) hamsters provide a model of postmenopausal atherosclerosis to investigate plaque formation in cerebral and systemic vasculature. The anti-atherogenic effects of flaxseed were studied by measuring the diameter of vessels using high resolution images acquired at high field (21.1 T). The animals were imaged at three time points: baseline, 4 months and 8 months. Atherosclerotic plaque formations were compared between sham, ovx, and ovx-flaxseed treated animals. No occlusions could be seen in cerebral arteries while differences were identified in the carotids and system circulation.

                  1281.     Ex Vivo MRI Assessment of USPIO Uptake in Aortic Plaque in a Mouse Model of Atherosclerosis at 11.7T

Haiying Tang¹, Sherif Fahmy², Dan Zhou¹, Tony Paiva¹, Todd Parrish², Jens H. Jensen³

¹Merck Research Laboratories, Rahway, NJ, United States; ²Northwestern University, Chicago, IL, United States; ³New York University School of Medicine, New York, NY, United States

In this study, we present ex vivo MRI assessment of USPIO uptake in aortic plaque in a mouse model of atherosclerosis at 11.7T. The purpose is to evaluate quantitative imaging methods for characterizing USPIO uptake in atherosclerotic plaque. Polymer solution phantoms, cell phantoms, and ex vivo studies were developed to help understand how different signal features are affected by the contrast agent for a variety of pulse sequences. Positive contrast techniques and susceptibility related imaging methods were compared. The goal is to determine which MRI metrics best reflect the contrast agent uptake for the purpose of quantification in living tissues.

Myocardial Viability: Human Studies

                  1282.     Non-Selective Double Inversion Recovery Pre-Pulse for Flow-Independent Black Blood Myocardial Viability Imaging

Sarah Anne Peel¹, Christian Jansen¹, Geraint Morton¹, Simon Duckett¹, Tobias Schaeffter¹, René M. Botnar¹

¹Division of Imaging Sciences, King's College London, London, United Kingdom

MRI late gadolinium enhancement using the inversion-recovery sequence is the current gold standard for the assessment of myocardial viability.  Although it achieves high contrast between infarct and normal myocardium, there is often poor infarct-to-blood contrast. We sought to improve infarct-to-blood contrast using a novel non-selective double inversion technique that provides flow-independent signal suppression over a wide user-defined T1-range. Simulations and phantom studies demonstrate excellent tissue suppression over a wide T1-range. Preliminary patient data show an improvement in infarct-to-blood CNR. This technique facilitates detection of sub-endocardial defects and has potential for more accurate quantification of infarct size and transmurality.

                  1283.     Realtime Free-Breathing Ungated Imaging of Cardiac Function and Viability Using an IR-Spiral-SSFP Sequence

Venkat Ramanan¹, Labonny Biswas¹, Jay Stephen Detsky¹, Rhonda Walcarius¹, Gideon A. Paul¹, Alexander J. Dick¹, Graham A. Wright¹

¹Imaging Research, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada

Free-breathing, Ungated Realtime imaging using inversion recovery cartesian SSFP has been proposed to assess myocardial function and viability. However since these techniques suffer from poor temporal resolution, we have designed Realtime IR-Spiral-SSFP to improve it. Several waveforms were designed and tested resulting in different spatial and temporal resolutions. We scanned a few patients with a spiral waveform of 88ms temporal resolution and 3mm spatial resolution. Preliminary results show that this is a viable imaging approach and there is scope for further improvement to improve the tradeoffs between spatial vs temporal resolution.

                  1284.     High Resolution MRI with a Spiral k-Space Trajectory: Atrial Wall Imaging and Late Gadolinium Enhancement for the Assessment of RF Ablation Lesion Transmurality in the Left Atrium.

Benjamin R. Knowles¹, Claudia Prieto¹, Reza Razavi¹, Tobias Schaeffter¹

¹Imaging Sciences, Kings College London, London, United Kingdom

Current late gadolinium enhancement (LGE) techniques for the visualisation of RF ablation lesions do not reach sufficient resolution to determine if ablation lesions are transmural, We have formed a strategy to assess ablation lesion transmurality using the combination of high resolution LGE and atrial wall imaging. Both MR scans use a spiral k-space trajectory as this trajectory is a highly efficient sampling scheme. Off-resonance effects are corrected for. High-resolution LGE images are compared to the lower resolution Cartesian LGE currently in use. Thickness measurements of the atrial wall and of the enhancing areas are conducted in order to assess transmurality.

                  1285.     3D Hybrid Radial Acquisition with Compressed Sensing for LGE Imaging of Left Atrium: A Simulation Study

Ganesh Adluru¹, Sathya Vijayakumar¹, Nathan Burgon², Eugene Kholmovski¹, Nassir Marrouche², Edward DiBella¹

¹Radiology, University of Utah, Salt Lake City, UT, United States; ²Cardiology, University of Utah, Salt Lake City, UT, United States

Atrial fibrillation currently affects over 7 million people in the U.S. and Europe. Late Gadolinium Enhancement (LGE) imaging offers a means to assess ablation of the left atrium and the pulmonary vein ostia.  Here we propose to reduce the scan time and improve the image quality over a standard 3D Cartesian acquisition (with respiratory and ECG gating) by (i) acquiring data using a stack of stars scheme and (ii) using compressed sensing reconstruction methods.  Results from simulated phantom and patient data show the feasibility of the method to obtain better image quality that may improve clinical utility of LGE imaging.

                  1286.     Late Gadolinium Enhancement Can Visualize the Periinfarct Zone in Acute Myocardial Infarction

Yoshiaki Morita¹, Naoaki Yamada², Teruo Noguchi³, Hiromi Hashimura², Tetsuro Nakazawa², Atsushi Kono², Suzu Kanzaki², Tetsuya Fukuda², Masahiro Higashi², Hiroaki Naito²

¹Department of Radiology , National Cardiovascular Center , Suita, Osaka , Japan; ²Department of Radiology, National Cardiovascular Center, Suita, Osaka, Japan; ³Division of Cardiology, National Cardiovascular Center, Suita, Osaka, Japan

Previous studies suggested that the periinfarct zone in acute myocardial infarction may provide the important prognostic information and serve as a therapeutic target. It is widely known that the hyperintense area in T2-weighted imaging closely matched the periinfarct zone. However, T2-weighted image is sometimes degraded by motion artifact and arrhythmia. In this study, we demonstrate that the early phase in late gadolinium enhancement (at the time of 2 minutes after gadolinium administration) can clearly visualize the periinfarct zone similar to or better than T2 map and offer robust diagnostic image quality compared to T2-weighted image.

                  1287.     Fast Quantitative Measurement of T1 in Cardiac Delay Enhanced Studies

Matteo Milanesi¹, Luca Marinelli², Christopher J. Hardy², Vincenzo Positano¹, Piergiorgio Masci¹, Andrea Barison¹, Maria F. Santarelli³, Luigi Landini⁴, Massimo Lombardi¹, Thomas K. Foo²

¹"G. Monasterio" Foundation, Pisa, Italy; ²Global Research Center, General Electric, Niskayuna, NY, United States; ³Institute of Clinical Physiology, National Research Council, Pisa, Italy; ⁴Department of Information Engineering, University of Pisa, Pisa, Italy

In this work a Cine Inversion Recovery pulse sequence is presented to quantify T1 values in myocardial delay enhancement studies. FastSPGR with low flip angle is used to sample the exponential spin relaxation during the first heart beat following an adiabatic inversion pulse. The subsequent heart beat is left to allow full T1 recovery. Four patients with suspicion of heart diseases were enrolled in the study, and acquisition carried out at 1.5T scanner. Cine-IR showed T1 values higher for viable myocardium than for non-viable. These and blood pool estimated T1, were found to be close to those reported in literatures.

                  1288.     Comparison of Gd-BOPTA and Gd-DPTA Late Gadolinium Enhancement for Visualizing Scar, Using Valve Enhancement as a Surrogate for Scar Adjacent to Blood

Dana C. Peters¹, Reza Nezafat¹, Peng Hu¹, Yuchi Han¹, Warren J. Manning^1,2

¹Cardiovascular Division, Beth Israel Deaconess Medical Center, Boston, MA, United States; ²Radiology, Beth Israel Deaconess Medical Center

The CNR (blood-fibrosis) of Gd-BOPTA was compared to Gd-DTPA, using a high resolution late gadolinium enhancement technique with 0.2mmol/kg injection and a 15-40 minute delay.  Eighteen patients were imaged with Gd-BOPTA, 8 of which were imaged with Gd-DTPA at another time point.    The valves were studied as a surrogate for scar which adjacent to blood.  The valve enhancement was greater using Gd-DTPA (p<0.05), Blood SNR was greater with Gd-BOPTA (p<0.05), and fibrosis blood CNR (measured in the valves) was greater for Gd-DTPA (p<0.05).  Gd-DTPA outperformed Gd-BOPTA at this dose for visualizing the valve enhancement.

                  1289.     Multicontrast Delayed Enhancement (MCODE) Newly Characterizes a Common Linear Delayed Enhancement Abnormality in the Anteroseptum of the Heart

Wiphada Patricia Bandettini¹, Christine Mancini¹, Peter Kellman¹, Andrew Ernest Arai¹

¹National Heart, Lung, and Blood Institute, Laboratory of Cardiac Energetics, National Institutes of Health, Bethesda, MD, United States

In this study, we present the use of multi-contrast delayed enhancement (MCODE) in trouble-shooting regions of high signal intensity within the myocardium that may be atypical delayed enhancement or may simply be blood pool adjacent to the epicardium and trabeculae.  Our initial results show the utility of MCODE in clarifying questions of possible delayed enhancement beyond that of myocardial infarction.  Furthermore, we demonstrate that a common region adjacent to the anteroseptum that has previously been thought to be blood pool between the septum and right ventricular moderator band or papillary muscle is in fact a tissue-based structure.

                  1290.     Myocardial T1-Mapping in Chronic Myocardial Infarction: Results of Unenhanced and Contrast Enhanced MR Imaging Using Gadobutrol

Kerstin Ulrike Bauner¹, Andreas Biffar², Daniel Theisen¹, Torleif Sandner¹, Andreas Greiser³, Maximilian F. Reiser¹, Bernd Wintersperger¹

¹Department of Clinical Radiology, LMU Munich - Campus Grosshadern, Munich, Germany; ²Josef Lissner Laboratory for Biomedical Imaging, LMU Munich - Campus Grosshadern, Munich; ³Siemens medical solutions

At a given field strength tissues present with specific T1-values. We hypothesize, that infarcted myocardial tissue can be delineated from normal myocardium by means of T1-maps in unenhanced and contrast-enhanced (Gadobutrol) scans. Analysis of T1-values was performed for normal myocardium (MYO), infarcted myocardium (CMI) and the left ventricular cavity (LVC). In addition T1-ratios of MYO/LVC and CMI/LVC were calculated. T1-values of MYO and CMI and the calculated ratios of MYO/LVC and CMI/LVC were significantly differenent in pre-contrast and post-contrast scans. MR-measurements of T1-values with the LVC as a reference allow for a differentiation of infarcted areas from normal myocardial tissue.

                  1291.     The Association of the Extent of Myocardial Infarction (MI) Detected by Magnetic Resonance Imaging (MRI) and the Quantification of Coronary Calcium by Computed Tomography (CT)

Gyda S. Karlsdottir¹, Sigurdur Sigurdsson¹, Thor Aspelund¹, Gudny Eiriksdottir¹, Jie J. Cao², Lenor Launer³, Tamara B. Harris³, Robert Detrano⁴, Andrew Arai⁵, Vilmundur Gudnason⁶

¹Icelandic Heart Association Research Institute, Kopavogur, Iceland; ²National Heart, Lung and Blood Institute, Bethesda, United States; ³IRP, National Institute on Aging, Bethesda, United States; ⁴University of California Irvine,, Irvine, United States; ⁵IRP, National Heart, Lung and Blood Institute, Bethesda, United States; ⁶¹Icelandic Heart Association Research Institute, Kopavogur, Iceland

Purpose of our study was to investigate the association of the extent of MI localized by gadolinium enhanced MRI, and the quantity of calcium in the coronary arteries detected with CT. Of the 674 subject, 21% had evidence of MI. Subjects with MI in all three coronary distributions had higher coronary calcium score (CCS), compared to those with MI in only one. Those with only one or two infarcted segments had significantly lower CCS than those with infarct in three or more segments. The relationship between the extent of MI and quantity of coronary calcium is significant and strong.

                  1292.     Segmented T2-Prepared SSFP for Myocardial T2-Weighted Imaging and T2-Mapping

Jeff A. Stainsby¹, Graham A. Wright²

¹Applied Science Laboratory, GE Healthcare, Toronto, Ontario, Canada; ²Imaging Research, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada

Recent studies demonstrate that hyperintense regions in T2-weighted images in acute myocardial infarction (AMI) reflect the presence of edema and area at risk. Single-shot T2-prepared SSFP methods have been presented for T2-weighted imaging in AMI. Here a segmented SSFP approach suitable for multi-slice, multi-echo imaging of the myocardium is presented.

                  1293.     A Comparison of Methods for T2-Mapping of the Myocardium

Jeff A. Stainsby¹, Venkat Ramanan², Glenn S. Slavin³, Graham A. Wright²

¹Applied Science Laboratory, GE Healthcare, Toronto, Ontario, Canada; ²Imaging Research, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada; ³Applied Science Laboratory, GE Healthcare, Bethesda, MD, United States

T2-weighted imaging in acute myocardial infarction has been suggested for detecting regions of edema. The need to carefully account for variations in coil sensitivity patterns has been noted with these techniques. An alternate approach is to generate quantitative T2 maps. In this work we compare 3 different myocardial T2 mapping methods; multi-echo double-IR FSE (MEFSE), segmented T2-prepared SSFP (T2pSSFP) similar to [1] and T2-prepared spiral (SpiralT2) [2].

                  1294.     Three-Compartment Pharmacokinetic Modeling of Chronic Myocardial Infarction Gadolinium Kinetics

James W. Goldfarb^1,2, Wenguo Zhao¹

¹Saint Francis Hospital, Roslyn, NY, United States; ²Program in Biomedical Engineering, Stony Brook University, Stony Brook, NY, United States

The aim of this study was to investigate the suitability of a three compartment pharmacokinetic model of late gadolinium-enhancement for chronic myocardial infarcts.  Twenty-five individuals with chronic myocardial infarctions (MI) underwent MR imaging at 1.5T.  Blood concentration was modeled with a bi-exponential and tissue concentration with a three compartment model, including vascular, free and trapping compartments.  Fractional volumes  and transfer constants into the compartments were fitted parameters of the model.  It was found that a three compartment model is suitable for detailed modeling of chronic MI Gd-pharmacokinetics.  This model provides further justification that fibrosis traps the Gd-contrast agent while Gd-concentrations in the free extracellular matrix remain similar with viable myocardium.

                  1295.     Quantitative Assessment of Microscopic Fibrosis in Patients with Primary Aldosteronism Using Dynamic Contrast Enhancement

Mao-Yuan Marine Su¹, Ven-Cent Wu², Hsi-Yu Yu³, Wen-Yih Isaac Tseng^1,4

¹Medical Imaging, National Taiwan University Hosptial, Taipei, Taiwan; ²Internal Medicine, National Taiwan University Hosptial, Taipei, Taiwan; ³Surgery, National Taiwan University Hosptial, Taipei, Taiwan; ⁴Center for Optoelectronic Biomedicine, National Taiwan University College of Medicine, Taipei, Taiwan

For patients with primary aldosteronism (PA), aldosterone induced diffuse and microscopic fibrosis in the myocardium is difficult to be detected on the images of late gadolinium enhancement (LGE) MRI. In this study, we proposed a dynamic contrast enhancement method to detect the presence of microscopic fibrosis. In patients with PA, our results showed a significantly lower down-slope index (1.10¡Ó0.16 vs. 1.29¡Ó0.21; p=0.02) and a significantly higher end-point value index (0.88¡Ó0.02 vs. 0.85¡Ó0.03; p=0.04) compared to the normal subjects. These findings indicate the delayed wash-out and prolonged retention of the contrast medium in the myocardium, and suggest that there is increased amount of microscopic fibrosis in the myocardium. Therefore, we conclude that the proposed dynamic contrast enhancement method is capable of detecting the presence of microscopic fibrosis.

                  1296.     Cardiac Magnetic Resonance and Dual-Source CT Detect Lipomatous Metaplasia of Left Ventricle in Chronic Myocardial Infarction

Yue Zang¹, Jie Zhou², Jian Wu³, Zhao Qi Zhang

¹Beijing Anzhen Hospital, Beijing, China; ²Beijing Anzhen Hospital, China; ³Beijing people's hospital of Peking University

we use cardiac magnetic resonance (CMR) and dual-source CT to detect fatty tissue to confirm the morphologic change. 8 Of the 11 patients with lipomatous metaplasia were identified by CMR(72.7%); In 5 cases (62.5%), the thickness of the fatty tissue less than half of the scar. 1.5T cine- CMR showed wall thinner and akinesia or hypokinesia. Non-contrast black-blood T1-weighted spin echo images revealed a high signal with dramatic signal decay after fat saturation £¬indicating the presence of intramyocardial fat. CT plan scan and coronary CT showed hypodensity £¨from -56 to -113 HU£©in the myocardium, the location and extent consistent with CMR findings.

                  1297.     Dark Blood Fat-Water Separated Cardiac Imaging Improves Delineation of Right Ventricular Myocardium

Peter Kellman¹, Diego Hernando², Saurabh Shah³, Z-P Liang², Andrew E. Arai¹

¹National Institutes of Health, Bethesda, MD, United States; ²University of Illinois, Urbana, IL, United States; ³Siemens Medical Solutions, Chicago, IL, United States

Fat-water imaging in the heart is important for detection of intramyocardial fat and characterizing fibro-fatty infiltration seen in ARVD and chronic MI. A dark blood prepared fat/water separated imaging protocol has been developed which provides improved delineation of the myocardium. This should improve the ability to discern fatty infiltration of the thin walled RV.

                  1298.     Cardiac Free-Breathing Balanced SSFP Cine Sequences: Radial Vs. Cartesian K-Space Reconstruction

Lorenzo Mannelli¹, Monvadi Barbara Srichai-Parsia², Daniel Kim¹, Xhafer Sinani², Rajesh Hiralal¹, Ruth P. Lim¹

¹Radiology, New York University, New Nork, United States; ²Radiology, Bellevue Hospital Center, New York, United States

In this study we compare free-breathing balanced SSFP cine sequences (radial vs. Cartesian K space reconstruction) in a short series of consecutive patients. Radial acquisitions have the potentiality to be one of the possible strategies in patients who are unable to breath-hold or who have significant arrhythmias where segmented SSFP cine imaging is challenging and suboptimal for left and right ventricle function assessment.

                  1299.     MR Imaging of Cardiac Wall-Motion at 1.5T and 7T: SNR and CNR Comparison

Stefan Maderwald^1,2, Kai Nassenstein, ¹², Stephan Orzada^1,2, Lena C. Schäfer^1,2, Mark Oehmigen¹, Andreas K. Bitz^1,2, Oliver Kraff^1,2, Irina Brote^1,2, Susanne C. Ladd^1,2, Mark E. Ladd^1,2, Harald H. Quick^1,3

¹Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, Germany; ²Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany; ³Institute of Medical Physics, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany

Increased SNR and enhanced soft tissue contrasts are anticipated for 7T high-field MRI in comparison to 1.5T. The expected increases in SNR and CNR are of particular interest for high-resolution cardiac MR applications in humans. After addressing some of the 7T related transmit/receive problems, five healthy volunteers were imaged at 1.5T and 7T to measure and to compare SNR and CNR of cardiac function sequences along the short axis. It can be concluded that with the demonstrated increases in SNR and CNR, 7T cardiac function MRI with spoiled gradient echo at 7T outperforms cardiac function MRI with SSFP at 1.5T.

                  1300.     Toward 7 Tesla Cardiac MRI for Clinical Application

Stefan Maderwald^1,2, Stephan Orzada^1,2, Lena C. Schäfer^1,2, Andreas K. Bitz^1,2, Kai Nassenstein, ¹², Oliver Kraff^1,2, Irina Brote^1,2, Mark Oehmingen¹, Susanne C. Ladd^1,2, Mark E. Ladd^1,2, Harald H. Quick^1,3

¹Erwin L. Hahn Institute for Magnetic Resonance Imaging, Essen, Germany; ²Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany; ³Institute of Medical Physics, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany

Highfield MRI at 7T inherently offers higher signal-to-noise and enhanced soft tissue contrasts when compared to 1.5T or even 3T MRI, which might improve image quality in selected imaging applications like high-resolution cardiac MRI in humans. To push cardiac MRI at 7T another step further, a number of artifacts and imaging constraints related to 7T transmit/receive problems have to be addressed first. Additionally, protocols already established for 1.5T and 3T cardiac imaging have to be evaluated. This study presents two RF coil concepts to tackle some transmit/receive issues and evaluates established cardiac protocols which have been modified for application at 7T.

                  1301.     NMR Molecular Profiling of Human Blood Plasma in Induced Myocardial Ischemia

Jose Manuel Morales¹, Fabian Chaustre², David Moratal³, Vicent Bodi⁴, Daniel Monleon²

¹Universitat de Valencia, Valencia, Spain; ²Fundacion Investigacion Hospital Clinico Valencia, Valencia, Spain; ³Center for Biomaterials and Tissue Engineering, Universitat Politecnica Valencia, Valencia, Spain; ⁴Hospital Clinico Universitario de Valencia, Valencia, Spain

The protocols of management of patients entering emergency rooms because thoracic pain of potential ischemic origin without necrosis include serial measurement s of biomarkers, stress tests and, in many cases, unnecessary hospitalization. In this context, detection of metabolic markers, which represent dynamic changes in just a few minutes after ischemia, is an attractive option both for diagnosis precision and for rapid and efficient management. In this communication, we used NMR metabolic profiling to characterize metabolically blood plasma of patients pre and post angioplasty. Statistical multivariate analysis showed differences in signals belonging mainly to ketonic bodies and fatty acids.

Myocardial Viability - Experimental Models

                  1302.     Combined Manganese-Enhanced MRI and DTI Methods to Assess Post-Myocardial Infarction Molecular and Structural Remodeling

Benjamin Waghorn^1,2, Wen Li^3,4, Xin Yu^3,4, Tom C.-C. Hu^1,2

¹Department of Radiology, Medical College of Georgia, Augusta, GA, United States; ²Nuclear and Radiological Engineering and Medical Physics Programs, Georgia Institute of Technology, Atlanta, GA, United States; ³Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States; ⁴Case Center for Imaging Research, Case Western Reserve University, Cleveland, OH, United States

Intracellular calcium overloading and structural changes are known to occur in the post-myocardial infarction (MI) heart. This study demonstrates the use of combined cardiac T₁-mapping manganese-enhanced MRI and DTI in a mouse MI model to examine the relationship between indirect Ca²⁺ handling and structural modification during the myocardial remodeling process. Decreased Mn²⁺ uptake was observed for the infracted tissue, as well as the ischemic peri-infarct tissue, with a decrease in diffusivity and an increase in diffusion anisotropy also observed in the infarct hearts. Results from this study could provide a method for monitoring the salvageability of the peri-infarcted zone.

                  1303.     Molecular Imaging of Myocardial Inflammation in Experimental Autoimmune Myocarditis Rats with Magnetofluorescent Nanoparticles

Hyeyoung Moon¹, Hyo Eun Park², Quan-Yu Cai¹, Jongeun Kang¹, Kiyuk Chang², Kwan Soo Hong¹

¹Magnetic Resonance Imaging Team, Korean Basic Science Institute, Ochang-Myun, Cheongwon-Gun, Korea, Republic of; ²Department of Internal Medicine, Catholic University, Seoul, Korea, Republic of

In this study, we investigated whether magnetic nanoparticle-contrasted cardiac magnetic resonance imaging would be feasible and effective for the detecting the inflammation in a rat model of experimental autoimmune myocarditis, and whether MNP-contrasted CMR imaging could give a guidance where the biopsy samples should be collected.

                  1304.     Rotating Frame, Spin Lattic Relaxation in a Swine Model of Late Ventricular Myocardial Infarction

Walter RT Witschey^1,2, James J. Pilla², Giovanni Ferrari², Keivn Koolmasingh², Mohammed Haris¹, Robin Hinmon², Gerald A. Zsido¹, Joseph H. Gorman III², Robert C. Gorman², Ravinder Reddy¹

¹Center for Magnetic Resonance and Optical Imaging, Department of Radiology, University of Pennsylvania, Philadelphia, PA, United States; ²Department of Surgery, University of Pennsylvania, Philadelphia, PA, United States

T1ρ MRI was performed to differentiate scar tissue, proximal, borderzone tissue and healthy myocardium in a swine model of left ventricular myocardial infarction. The spatially-dependent relaxation times were validated by histological staining of collagen and myocytes. Significant magnetic relaxation dispersion with the application of a varying amplitude RF field was observed. These results suggest that T1ρ is superior to conventional methods such as T2 for the visualization of early edema and late scarring and expansion in patients with ischemic cardiomyopathy.

                  1305.     Myocardial Extracellular Volume Imaging - Phantom Validation and Patient Feasibility for Quantitative Pixel Mapping of the Fractional Distribution Volume of Extracellular Contrast Agents by MRI

Martin Ugander¹, Abiola J. Oki¹, Peter Kellman¹, Andreas Greiser², Anthony H. Aletras¹, Andrew E. Arai¹

¹National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, United States; ²Siemens AG Healthcare Sector, Erlangen, Germany

T1-mapping of the heart before and after intravenous contrast administration can be used to generate quantitative pixel-maps of the extracellular volume (ECV) fraction of the myocardium in patients. The study presents comprehensive phantom, experimental and patient validation of the T1 mapping sequence (MOLLI) which is used to calculate ECV. The method provides images for quantitative assessment of the ECV of the myocardium, and in principle any other tissue, in a pixel map with a quantitative color scale ranging from 0-100%.

                  1306.     Tracking Edema, Hemorrhage and Microvascular Obstruction by MRI After Acute Myocardial Infarction

Nilesh R. Ghugre¹, Venkat Ramanan¹, Mihaela Pop², Yuesong Yang¹, Jennifer Barry¹, Beiping Qiang¹, Kim Connelly³, Alexander J. Dick¹, Graham A. Wright^1,2

¹Imaging Research, Sunnybrook Health Sciences Centre, Toronto, ON, Canada; ²Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada; ³Division of Cardiology, St. Michael's Hospital, Toronto, ON, Canada

Pathophysiological responses after acute myocardial infarction (AMI) include edema, hemorrhage and microvascular obstruction (MVO) along with cellular damage. The in vivo evolution of these processes throughout infarct healing has not been well characterized. The purpose of our study was to monitor the time course of edema (T2), hemorrhage (T2*) and MVO in porcine myocardium following AMI and to observe the relative resolution of these pathophysiological mechanisms. Our study suggests that quantitative T2 and T2* mapping techniques are potentially more specific than intensity measures in single images, allowing regional, longitudinal and cross-subject comparisons. Such in vivo characterization will be important in grading severity and evaluating treatment strategies in AMI, potentially improving clinical outcome.

                  1307.     On the Mechanism of Myocardial Edema Contrast in SSFP Imaging

Xiangzhi Zhou¹, Veronica Rundell¹, Ying Liu¹, Richard Tang¹, Rachel Klein¹, Shivraman Giri², Saurabh Shah³, Sven Zuehlsdorff³, Orlando Simonetti², Debiao Li¹, Rohan Dharmakumar¹

¹Northwestern University, Chicago, IL, United States; ²Ohio State University, Columbus, OH, United States; ³Siemens Medical Solutions USA, Inc., Chicago, IL, United States

The mechanism of bSSFP edema contrast in acute myocardial infarction imaging is not well understood. To assess the various mechanisms that enable the detection of myocardial edema on the basis on bSSFP imaging, controlled experiments were conducted in canine models subjected to ischemia reperfusion injury. Results show that relaxation and M0 changes have significant contribution to the detection of edematous myocardial zones following acute injury to the myocardium on the basis bSSFP imaging.

                  1308.     On the Origin of Myocardial Edema Contrast in T2-STIR Images

Xiangzhi Zhou¹, Veronica Rundell¹, Ying Liu¹, Richard Tang¹, Rachel Klein¹, Shivraman Giri², Saurabh Shah³, Sotirios A. Tsaftaris¹, Sven Zuehlsdorff³, Orlando Simonetti², Debiao Li¹, Rohan Dharmakumar¹

¹Northwestern University, Chicago, IL, United States; ²Ohio State University, Columbus, OH, United States; ³Siemens Medical Solutions USA, Inc., Chicago, IL, United States

The biophysical mechanisms contributing to myocardial edema contrast in T2-weighted STIR images was studied using dogs subjected to ischemia-reperfusion injury. It is shown that in addition to T2-weighting, edema detection in acute myocardial infarcts with T2-weighted STIR images have substantial weighting from proton density changes. This finding suggests that myocardial edema detection sensitivity is enhanced when acquisition strategies permit sensitivity to proton density, as well as T2 changes.

Myocardial Perfusion: Experimental Model & Human Studies

                  1309.     Arterial Spin Labeled MRI Detects Increase in Myocardial Blood Flow with Adenosine

Zungho Zun¹, Padmini Varadarajan², Ramdas G. Pai², Eric C. Wong³, Krishna S. Nayak¹

¹Department of Electrical Engineering, University of Southern California, Los Angeles, CA, United States; ²Division of Cardiology, Loma Linda University Medical Center, Loma Linda, CA, United States; ³Departments of Radiology and Psychiatry, University of California, San Diego, La Jolla, CA, United States

Myocardial arterial spin labeling (ASL) scans were performed at rest and during adenosine infusion in eleven patients scheduled for CMR. Seven patients were classified as normal based on having no visible perfusion defect on CMR first-pass imaging.  In these subjects, there was a statistically significant increase in global myocardial blood flow (MBF) measured during adenosine infusion (3.75 ± 1.06 ml/g/min), compared to at rest (1.09 ± 0.53 ml/g/min).  This suggests that myocardial ASL may be capable of capturing clinically relevant increases in MBF with vasodilation.

                  1310.     Magic Angle Spinning MRS for Identifying Biomarkers of Perfusion Preservation of Human Hearts After 12 Hour Storage

Michael L. Cobert¹, Matthias Peltz¹, Matthew E. Merritt², LaShondra M. West¹, Larry Ammann³, Michael E. Jessen¹

¹Cardiovascular and Thoracic Surgery, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, United States; ²Advanced Imaging Research Center, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, United States; ³Mathematics, University of Texas at Dallas, Dallas, TX, United States

Perfusion preservation of donor hearts appears promising for extending the donor ischemic interval and utilization of extended donors. A major risk of using so-called marginal donors is predicting the viability of the graft. The current study utilizes proton magic angle spinning spectroscopy to determine biomarkers of perfusion preservation. These data suggest MAS MRS may be useful for determining heart function prior to implantation

                  1311.     Three-Dimensional Myocardial Perfusion MRI Using SW-CG-HYPR

Lan Ge¹, Heng Ma², Aya Kino¹, James Carr¹, Kuncheng Li, Debiao Li¹

¹Departments of Radiology and Biomedical Engineering, Northwestern University, Chicago, IL, United States; ²Xuanwu Hospital and Capital Medical University, Beijing, China

Image quality and spatial coverage for myocardial perfusion MRI are limited in current approaches. In this work, we developed a 3D inversion recovery (IR) prepared Turbo-FLASH sequence with radial sampling, combined with SW-CG-HYPR for myocardial perfusion MR imaging. Using this method, the acquisition time per partition in each cardiac cycle was reduced dramatically, and 6 partitions were acquired after each IR pre-pulse. The signal changes of the left ventricle and myocardium were verified by comparison to conventional methods. Mean correlation coefficients between 3D SW-CG-HYPR and reference images are 0.98, 0.96 for blood and myocardial signals, respectively.

                  1312.     Improved Reliability of Cardiac Perfusion MRI Using Free-Breathing Myocardial ASL with Navigator-Echo (FREEMAN)

Jiongjiong Wang¹, Xiaoming Bi², Tongbai Meng³, Sven Zuehlsdorff², John A. Detre⁴

¹Radiology, University of Pennsylvania, Philadelphia, PA, United States; ²Cardiovascular MR R&D, Siemens Healthcare, Chicago, IL, United States; ³Center for Applied Medical Imaging, Siemens Corporate Research, Baltimore, MD, United States; ⁴Neurology, University of Pennsylvania, Philadelphia, PA, United States

Arterial spin labeling (ASL) has been applied for noninvasive measurement of myocardial blood flow (MBF), yet the reliability is not optimal due to the requirement for repeated breath holding. We developed a cardiac ASL technique for reliable clinical applications – dubbed FREE-breathing Myocardial ASL with Navigator-echo (FREEMAN). Dynamic myocardial perfusion signals were measured at multiple delays. The estimated mean MBF was 103±56ml/100g/min with a mean transit time of approximately 400ms and moderate to high test-retest reliability.

                  1313.     4D BSSFP Myocardial BOLD Imaging with Flow Compensation: Early Results

Xiangzhi Zhou¹, Zhaoyang Fan¹, Richard Tang¹, Rachel Klein¹, Debiao Li¹, Rohan Dharmakumar¹

¹Northwestern University, Chicago, IL, United States

Cardiac phase-resolved 3D BOLD bSSFP imaging with first-order gradient moment compensation was studied in healthy dogs and those with coronary artery stenosis in the presence of adenosine stress. Flow/motion artifacts were greatly reduced in

3D cine bSSFP images in the presence of flow compensation compared to no flow compensation. In the presence of adenosine infusion, LCX stenosis led to a discriminating signal loss in the inferior walls that was readily visible in all cardiac phases in the flow compensated 3D cine bSSFP images.

                  1314.     Myocardial BOLD Imaging Using Flow Compensated 2D Cine BSSFP

Xiangzhi Zhou¹, Sotirios A. Tsaftaris¹, Ying Liu¹, Richard Tang¹, Rachel Klein¹, Sven Zuehlsdorff², Debiao Li¹, Rohan Dharmakumar¹

¹Northwestern University, Chicago, IL, United States; ²Siemens Medical Solutions USA, Inc., Chicago, IL, United States

Robust image quality is critical for reliable detection and evaluation of myocardial oxygenation changes with bSSFP BOLD imaging. This work evaluates the utility of 2D first-order motion compensation scheme to minimize flow/motion artifacts in cardiac phase-resolved bSSFP BOLD imaging using canines. Results show that compared to non-flow compensated bSSFP BOLD method, the proposed approach permits the evaluation of BOLD changes originating from coronary stenosis throughout the cardiac cycle.

                  1315.     Myocardial BOLD Imaging at 3T Using Quantitative T2: Application in a Myocardial Infarct Model

Nilesh R. Ghugre¹, Venkat Ramanan¹, Mihaela Pop², Yuesong Yang¹, Jennifer Barry¹, Beiping Qiang¹, Kim Connelly³, Alexander J. Dick¹, Graham A. Wright^1,2

¹Imaging Research, Sunnybrook Health Sciences Centre, Toronto, ON, Canada; ²Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada; ³Division of Cardiology, St. Michael's Hospital, Toronto, ON, Canada

Coronary vasodilatory dysfunction has been shown in infarcted as well as remote myocardium in patients with acute coronary syndrome. Our study demonstrates the utility of T2-based BOLD effect in probing regional and longitudinal fluctuations in vasodilatory function in a porcine model of myocardial infarction at 3T. T2 measurements were performed in remote and infarcted myocardium at rest and after Dipyridamole-induced vasodilation (stress). Experimental observations indicated that T2 at 3T offers greater sensitivity towards detecting changes in myocardial oxygenation compared to 1.5T, consistent with a two-compartment theoretical model. Stress-induced vasodilatory response using quantitative T2 can help evaluate remote-zone vascular function and potentially identity salvageable myocardium in the infarct zone.

MRS of the Heart

                  1316.     MRI/MRS Biomarkers for Response Evaluation in Patients with CABG

Zhuoli Zhang¹, Shengyong Wu², Ying Liu³, Savita Puri⁴, Shara Ramaswamy⁵, Yi Huan³, Debiao Li¹

¹Northwestern University, Chicago, IL, United States; ²Tianjin Medical University; ³Fourth Military Medical University; ⁴University of Rochester Medical Center; ⁵Florida International University

Phosphorus-31 magnetic resonance spectroscopy (31P-MRS) represents a unique instrument to noninvasively monitor myocardial metabolism in humans. The technique has been used to study the metabolism in myocardium in patients with coronary artery disease (CAD).  The measurements permit quantitative estimation of the phosphocreatine (PCr)/adenosine triphosphate (â-ATP) ratio which reflects the energetic state of the myocardium. Previous studies investigated the effect of successful coronary artery bypass grafting surgery (CABG) upon left ventricular function. Although residual myocardial viability in patients with CAD and extensive regional asynergy is associated with improved ventricular function after CABG, the relationship between myocardial metabolism and heart function after CABG remains unclear. We hypothesized that cardiac function benefits from high-energy phosphate (HEP) and sought to investigate the relationship between HEP and cardiac function in CAD patients using cine magnetic resonance imaging (cine-MRI) and 31P-MRS.

                  1317.     Cardiac Lipid Content as Determined by Magnetic Resonance Spectroscopy Increases After Exercise Protocol in the Fasted State

Vera Schrauwen-Hinderling¹, Lena Bilet¹, Tineke van de Weijer¹, Matthijs Hesselink¹, Jan Glatz¹, Joachim Wildberger¹, Michael Schär^2,3, Eline Kooi¹, Patrick Schrauwen¹

¹Maastricht University Medical Center, Maastricht, Netherlands; ²Johns Hopkins University, Baltimore, United States; ³Philips Health Care, Cleveland, United States

Excessive lipid accumulation in the myocardium may predispose to cardiomyopathy. Elevated plasma (free) fatty acids (FA) might be a risk factor herein. Cardiac lipid content was determined by 1H-MRS in healthy men (fasted state). Subsequently, subjects cycled for two hours and rested for three hours, after which cardiac lipid content was measured again. All subjects performed this protocol twice: once fasted and once while ingesting glucose to keep FA low. Cardiac lipid content was elevated after the fasted test day but unchanged when glucose ingestion kept FA low. This suggests that FA are important in determining cardiac lipid content.

                  1318.     The Role of Cardiac Carbonic Anhydrases in Vivo: A Hyperpolarised ¹³C MR Study

Marie Allen Schroeder¹, Pawel Swietach¹, Philip Lee², Ferdia A. Gallagher^3,4, Ben Rowlands¹, Claudiu T. Supuran⁵, Kevin M. Brindle, ^4,6, Richard D. Vaughan-Jones¹, George K. Radda^1,2, Kieran Clarke¹, Damian J. Tyler¹

¹Physiology, Anatomy and Genetics, University of Oxford, Oxford, Oxfordshire, United Kingdom; ²Biomedical Sciences Institute, Singapore Bioimaging Consortium, Singapore, Singapore; ³Radiology, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom; ⁴Li Ka Shing Centre, CRUK Cambridge Research Institute, Cambridge, United Kingdom; ⁵Dipartimento di Chimica, University of Florence, Florence, Italy; ⁶Biochemistry, University of Cambridge, Cambridge, United Kingdom

Carbonic anhydrase (CA) catalyses the hydration of CO₂ to form HCO₃- and H+, an inter-conversion which serves as a major pH buffer in blood plasma and inside cells. To date, cardiac isoforms of CA have only been studied in vitro, where their function could be drastically different than in vivo. The aim of this study was to determine the effects of intra- and extracellular isoforms of CA on CO₂ efflux from the heart, in vivo, based on MRS detection of ¹³CO₂ generated from the metabolism of hyperpolarised [1-¹³C]pyruvate. Our results indicated that extracellular CAs do not affect cardiac CO₃ removal under control perfusion conditions, though may have a role in ischemia. Further, we observed that intracellular CA activity trapped HCO₃- and H+ within the myocyte, which could potentially acidify the intracellular space. Physiological levels of cardiac intracellular CA must balance retention of myocardial bicarbonate to buffer potential acid/base disturbances, without causing excessive intracellular acidification.

                  1319.     Evaluation for Optimal Stress System for Cardiac MR Study

Hee-Won Kim^1,2, Karam Souibri³, Gerald M. Pohost^1,4

¹Radiology, University of Southern California, Los Angeles, CA, United States; ²Cardiology, Heart and Vascular Institute, Hollywood Presbyterian Hospital, Los Angeles, CA, United States; ³Cardiology, University of Southern California, Los Angeles, CA, United States; ⁴Electrical Engineering, University of Southern California, Los Angeles, CA, United States

A stress control system was developed and evaluated to obtain improved precision of the stress MR studies. The stability in stress was achieved by the feed-forward or feedback control and audio-visual stimulation actuated by the error signal. The system performance was evaluated by cardiac P-31 MRS at 3T. With the control system, it was clearly demonstrated that the stress level is far more stable during the entire session and inter-subject variation in the metabolic alterations is significantly reduced. It is expected to assess cardiac function and metabolite alteration during moderate stress with higher precision by using automatic stress control system.

                  1320.     The Effects of Fasting on Myocardial Lipid Content in Fatty Acid β-Oxidation Deficient Mice Studied with in Vivo ¹H-MRS

Adrianus Johannes Bakermans¹, Sander M. Houten², Tom R. Geraedts¹, Michel van Weeghel², Klaas Nicolay¹, Jeanine J. Prompers¹

¹Biomedical Engineering, Eindhoven University of Technology, Eindhoven, Netherlands; ²Laboratory Genetic Metabolic Diseases, Academic Medical Centre, Amsterdam, Netherlands

A respiratory gated, cardiac triggered PRESS ¹H-MRS sequence was used to investigate effects of fasting on lipid content in the long chain acyl-coenzyme A dehydrogenase knockout (LCAD^-/-) mouse heart. Left ventricular (LV) function and morphology were assessed using cine MRI. LV mass normalized to body weight was larger in LCAD^-/- mice than in controls, indicating LV hypertrophy. There was a trend for a decrease in ejection fraction after fasting, accompanied by increased lipid content in LCAD^-/- mice compared to controls. It remains to be established whether there is a causal relationship between increased myocardial lipid content and decreased cardiac function.

                  1321.     Navigator Gated and Cardiac Triggered Echo-Planar Spectroscopic Imaging of the Heart

Kilian Weiss¹, Nicola Martini², Peter Boesiger¹, Sebastian Kozerke¹

¹Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland; ²Interdepartmental Research Center "E. Piaggio", University of Pisa, Pisa, Italy

Single-voxel proton magnetic resonance spectroscopy has been shown to be a promising tool for assessing creatine and myocardial triglycerides in humans. While spectral information from a single volume is sufficient when alterations with global effects on the heart are studied, a demand for higher and flexible spatial resolution exists when probing local changes. To this end, implementation of fast spectroscopic imaging of the heart is desired. The objective of the current work was to implement and optimize navigator gated and cardiac triggered Echo-Planar Spectroscopic Imaging (EPSI) for assessment of triglyceride and creatine content in the myocardium in vivo.

                  1322.     Cardiac Lipid Content and Systolic Function in Overweight Type 2 Diabetic Subjects After Exercise Training

Vera Schrauwen-Hinderling¹, Ruth Meex¹, Jan Glatz¹, Joachim Wildberger¹, Hildo Lamb², Michael Schär^3,4, Matthijs Hesselink¹, Patrick Schrauwen¹, Marianne Eline Kooi¹

¹Maastricht University Medical Center, Maastricht, Netherlands; ²Leiden University Medical Center, Leiden, Netherlands; ³Johns Hopkins University, Baltimore, United States; ⁴Philips Health Care, Cleveland, United States

Excessive cardiac lipid storage might hamper cardiac function via ‘lipotoxic’ pathways. We investigated the response of cardiac lipids to exercise training in patients with type 2 diabetes mellitus. Maximal whole body oxygen uptake and LV-ejection fraction (by CINE-MRI) were improved while cardiac lipid content (by 1H-MRS) was unchanged after training. This is in contrast to our earlier findings in healthy overweight subjects, where such a training intervention diminished cardiac lipid content. This may indicate hampered exercise-induced lipid mobilization in the diabetic heart and reveals that reduction of cardiac lipids is not a prerequisite for the training-induced improvement in cardiac function.

                  1323.     Myocardial Steatosis Is Associated with Regional Ventricular Dysfunction

Chia-Ying Liu¹, Alban Redheuil¹, Elzbieta Chamera¹, Joao Lima¹, David Bluemke², Shenghan Lai³

¹Department of Radiology, Johns Hopkins Hospital, Baltimore, MD, United States; ²Radiology and Imaging Sciences, National Institutes of Health, Bethesda, MD, United States; ³Department of Epidemiology, Johns Hopkins School of Hygiene and Public health, Baltimore, MD, United States

The increased myocardial triglyceride pool is associated with impaired myocardial function in animal experiments. Human studies also indicate that myocardial steatosis is associated with impaired left ventricular filling dynamics and diastolic dysfunction. Proton Magnetic Resonance Spectroscopy (1H-MRS) has proven to be reliable and reproducible in measuring myocardial triglyceride content in humans. The primary goal of the present study was to evaluate the myocardial fat content in cardiovascularly asymptomatic HIV infected and non-infected individuals using 1H-MRS, and to correlate the septal triglyceride content to the regional ventricular function measured by tagged MRI.

                  1324.     Intramyocardial Lipid Quantification by MRS:  in Vivo Validation in Human Subjects

Robert D. O'Connor¹, Jian Xu², Linda R. Peterson³, Gropler J. Robert¹, Adil Bashir¹

¹Radiology, Washington University, St. Louis, MO, United States; ²Siemens, NY, United States; ³Internal Medicine, Washington University, St. Louis, MO, United States

An MRS assay of myocardial lipid is characterized and its accuracy and specificity cross-validated with ex vivo high resolution NMR measurements via endomyocardial biopsies from heart transplant patients.

                  1325.     Exploration of Mitochondrial Respiration in Isolated Hearts: An Observation from Metabolically Produced H₂¹⁷O Using ¹⁷O NMR Spectroscopy

Ming Lu^1,2, Jessica Spires¹, Gheorghe D. Mateescu^2,3, Chris Flask^2,4, Xin Yu^1,2

¹Biomedical Engineering, Case Western Reserve University, Cleveland, OH, United States; ²Case Center for Imaging Research, Case Western Reserve University, Cleveland, OH, United States; ³Chemistry, Case Western Reserve University; ⁴Radiology, Case Western Reserve University, Cleveland, OH, United States

Cardiac applications of ¹⁷O NMR for evaluating mitochondrial function have been limited due to the challenge of detecting metabolic H₂¹⁷O in the vast background of natural abundance H₂¹⁷O. In this study, we developed a direct ¹⁷O MR Spectroscopy (MRS) approach to examine the feasibility and sensitivity of detecting metabolically produced H₂¹⁷O in isolated rat hearts perfused with ¹⁷O₂-enriched Krebs buffer. Mitochondrial production of H₂¹⁷O was monitored by dynamic ¹⁷O spectroscopy. Oxygen consumption rate (MVO₂) was determined by least-square fitting of a compartmental model to NMR data. An increase of MVO₂ was observed under elevated workload induced by high Ca²⁺ concentration.

                  1326.     In Vivo T1 Mapping of ³¹P Metabolites at Short TR

Mahon L. Maguire¹, Hannah Barnes¹, Stefan Neubauer¹, Jurgen E. Schneider¹

¹Dept Cardiovascular Medicine, University of Oxford, Oxford, Oxon, United Kingdom

Quantitation of the energetics of the heart requires accurate tissue specific T1 values for the ³¹P metabolites involved.   Acquisition of ³¹P spectroscopic data at high resolution necessitates the use of a short TR relative to the T1 of the metabolites.  High resolution ³¹P chemical shift imaging was employed to take spatially resolved 2, 3 and 4 flip angle T1 measurements.  Phantom studies are presented investigating the optimal parameters for T1 mapping in vivo.  A dual angle T1 measurement employing flip angles of 30 and 15° is optimal where TR/T1<0.2; its application in the mouse is presented.

                  1327.     Performance of a Phased Array for ³¹P Cardiac MR Spectroscopy

Christopher T. Rodgers¹, Lowri E. Cochlin², Damian J. Tyler², Stefan Neubauer¹, Matthew D. Robson¹

¹Oxford Centre for Clinical Magnetic Resonance Research, University of Oxford, Oxford, United Kingdom; ²Department of Physiology, Anatomy and Genetics, University of Oxford, United Kingdom

Cardiac ³¹P spectra of high-energy phosphorus metabolites are typically acquired using a transmit/receive surface coil. In MR imaging, single element surface coils have largely been superseded by receive arrays, which provide higher signal-to-noise ratios (SNRs) and larger fields of view (FOVs). We present the first receive array cardiac ³¹P spectra at 3T. Comparing with an established protocol in 8 normal volunteers, we observe larger FOV and homogeneity, increased comfort, and an enhancement in SNR comparable to that from NOE. Our 8-element array contains for the first time posterior elements, which contribute up to 35% at the posterior of the heart.

                  1328.     Association Between Echocardiographic Epicardial Adipose Tissue (EAT) Thickness and 1H-MRS Septal Myocardial Fat

Giovanni Di Leo¹, Alexis Malavazos, Francesco Secchi, Calin Coman, Lelio Morricone, Massimiliano Marco Corsi, Gianluca Iacobellis², Francesco Sardanelli¹

¹Unit of Radiology, Università degli Studi di Milano, IRCCS Policlinico San Donato, San Donato Milanese, Milan, Italy; ²McMaster University

We assessed whether the epicardial adipose tissue (EAT) thickness is associated to the septal myocardial fat (SMF). Ten obese volunteers underwent echocardiographic EAT thickness measurement, 1.5-T 1H-MRS for SMF quantification (water reference) and MRI for EAT volume estimation. Intra- and interobserver reproducibility was excellent. SMF was 1-9%, EAT volume was 5-43 mL and EAT thickness was 3-11 mm. SMF showed a high correlation with EAT thickness, EAT volume, left ventricle mass and waist circumference. In multivariate regression, the EAT thickness was the only significant covariate of the SMF. We can speculate that EAT accumulation could reflect SMF in obese individuals.

                  1329.     Malate-Aspartate Shuttle Reversal Allows for Lactate Concentration Increases Upon Rapid Changes in ¹³C Pyruvate Concentration

Karlos X. Moreno¹, Scott Sabelhaus¹, Matthew E. Merritt¹, A Dean Sherry¹, Craig R. Malloy¹

¹Advanced Imaging Research Center, Univ of TX Southwestern Med Ctr, Dallas, TX, United States

The effect of [3-¹³C]pyruvate on [lactate] and [alanine] was studied in Langendorff-mode rat hearts.  A 90 second perfusion with 2 mM [3-¹³C]pyruvate increased [lactate] and [alanine].  During the inhibition of aminotransferases by AOA, an increase in [alanine] was not observed, but, unexpectedly, [lactate] did not increase either.  Lactate production was inhibited due to the lack of NADH replenishment from the malate-aspartate shuttle.  These results support a reversal of the malate-aspartate shuttle to provide NADH for the production of lactate following a rapid increase in [pyruvate].

                  1330.     Feasibility of Quantifying Lipid Content in Muscles, Liver and Heart of Very Obese Subjects with MRS

Ronald Ouwerkerk¹, Ahmed Medhat Gharib¹, Khaled Zakarya Abd-Elmoniem¹, Kong Y. Chen², Jatin Raj Matta¹, Monica C. Skarulis²

¹Cardiovascular Imaging, NIH, NIDDK, Bethesda, MD, United States; ²Clinical Endocrinology, NIH, NIDDK, Bethesda, MD, United States

To study effects of obesity on lipid metabolism in the muscles, heart and liver we studied obese subjects with localized MRS in heart, liver and leg muscles. A protocol comprising cardiac cine- and tagged MRI, water-fat images of liver, thigh and calf and a visceral fat determination was executed in a wide-bore 3T whole body magnet on subjects with body mass indices 41-62, weights 99-152kg. MRS data from PRESS with cardiac, navigator gating and outer volume suppression to reduce motion artifacts and contamination from surrounding fat proved feasibility of measuring cardiac, liver and skeletal muscle lipid content in obese subjects.

Flow Quantification: Vessel Function

                  1331.     T₂-Weighted Fourier Velocity Encoding: MR Oximetry in Small Vessels

Christopher Marek Wernik¹, Venkat Ramanan², Graham A. Wright^1,2, Christopher K. Macgowan^1,3

¹Dept. of Medical Biophysics, University of Toronto, Toronto, ON, Canada; ²Imaging Research, Sunnybrook Health Sciences Centre, Toronto, ON, Canada; ³Dept. of Diagnostic Imaging, Hospital for Sick Children, Toronto, ON, Canada

MR oximetry based on quantitative T2 measurement is a noninvasive technique for measuring blood oxygen saturation. However, partial volume effects limit T2 accuracy in narrow vessels or impose long scan times at reduced SNR. In this study, we propose an improved technique which uses Fourier velocity encoding to control for partial volume effects and test its feasibility using an apparatus that mimics constant blood flow in a vessel. The results show that the proposed technique is more accurate than conventional MR oximetry in the presence of partial volume effects. Considerations for in vivo application are discussed.

                  1332.     Evaluation of Different Techniques for Measuring Pulse Wave Velocity Using 3 Tesla MRI

Elsayed H. Ibrahim¹, Kevin R. Johnson¹, Jean M. Shaffer¹, Richard D. White¹

¹University of Florida, College of Medicine, Jacksonville, FL, United States

Arterial stiffness can be noninvasively estimated by measuring pulse wave velocity(PWV) from velocity-encoded MR images using different methods: transit-time(TT), flow-area(QA), and cross-correlation(XC). However, the reproducibility and comparison of these different techniques have not yet been studied in a large diverse group of patients for relative durability and reproducibility, especially at 3T field. In this work, the aortic PWV is measured in 50 patients, representing a wide range of cardiovascular conditions, to assess inter-observer, intra-observer, inter-scan, and inter-method variabilities using 3T MRI. The TT method resulted in the most-reproducible measurements and required the shortest processing-time, followed by XC and QA.

                  1333.     Accelerated Dual Velocity Encoded Phase Contrast VIPR

Elizabeth Janus Nett¹, Kevin M. Johnson¹, Christopher J. Francois², Darren Lum², Oliver Wieben, ^2,3

¹Medical Physics, University of Wisconsin , Madison, WI, United States; ²Radiology, University of Wisconsin, Madison, WI, United States; ³Medical Physics, University of Wisconsin, Madison, WI, United States

We present a method for improving the VNR in 3D radial undersampled phase contrast exams using an accelerated dual Venc acquisition.  This method will allow for more accurate velocity measurements and advanced hemodynamic analysis, particularly in vascular areas that have wide ranges of velocities of interest such as arterial and venous systems .

                  1334.     Probabilistic Flow Connectivity Mapping

Ola Friman¹, Anja Hennemuth¹, Andreas Harloff², Jelena Bock³, Michael Markl³, Heinz-Otto Peitgen¹

¹Fraunhofer MEVIS, Bremen, Germany; ²Neurology and Clinical Neurophysiology, Albert-Ludwigs Universität, Freiburg, Germany; ³Diagnostic Radiology, Medical Physics, Albert-Ludwigs Universität, Freiburg, Germany

Standard techniques for visualizing and quantifying flow data obtained with phase contrast (PC) MRI treat the measurements as if they were free of noise. This practice may lend the results a false sense of precision. This work contributes a flow connectivity mapping algorithm that models the noise in PC MRI velocity measurements and visualizes the flow uncertainty as a probabilistic flow distribution. New probabilistic measures such as the assignment of likelihoods to flow pathways to evaluate mixing of blood, or to quantify embolization probabilities in stroke and infarction, are also envisaged.

                  1335.     Age-Related Changes of Regional Pulse Wave Velocity in the Descending Aorta Using Fourier Velocity Encoded MR M-Mode

Valentina Taviani¹, Stacey S. Hickson², Christopher J. Hardy³, Andrew James Patterson¹, Carmel M. McEniery², Ian B. Wilkinson², Jonathan Harvey Gillard¹, Martin J. Graves¹

¹Department of Radiology, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom; ²Clinical Pharmacology Unit, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom; ³GE Global Research, Niskayuna, NY, United States

Age-related changes of regional aortic compliance play a crucial role in the pathophysiology of cardiovascular disease. Fourier velocity encoded (FVE) M-mode can produce Doppler-like time-velocity traces with high temporal and spatial resolution along relatively straight arterial segments. In this work, FVE M-mode was used to measure global and regional pulse wave velocity (PWV) in the descending aorta of 56 healthy subjects. A significant nonlinear relationship between overall PWV and age was found (r2=0.73, p<0.001). The distal thoracic aorta was found to stiffen the most with age, followed by the proximal and distal abdominal aorta.

                  1336.     Accuracy and Repeatability of Fourier Velocity Encoded M-Mode and 2D Cine Phase Contrast for Pulse Wave Velocity Measurement in the Descending Aorta

Valentina Taviani¹, Andrew James Patterson¹, Martin J. Graves¹, Christopher J. Hardy², Pauline W. Worters³, Michael P. Sutcliffe⁴, Jonathan Harvey Gillard¹

¹Department of Radiology, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom; ²GE Global Research, Niskayuna, NY, United States; ³Department of Radiology, Stanford University, Lucas Center, Stanford, CA, United States; ⁴Department of Engineering, University of Cambridge, Cambridge, United Kingdom

Accuracy and repeatability of pulse wave velocities (PWVs) obtained from Fourier velocity encoded (FVE) M-mode and 2D phase contrast (PC) with through-plane velocity encoding were investigated using five different analysis techniques. Accuracy was tested on a tubular human-tissue-mimicking phantom integrated into a flow simulator. The gold standard was obtained from the Moens-Korteweg equation after measurement of the tube elastic modulus by uniaxial tensile testing. Repeatability was evaluated across three MR visits. Similarly accurate results were obtained with the two MR techniques, provided the optimal algorithm was used. M-mode PWVs were more repeatable than PC PWVs, regardless of the analysis technique.

                  1337.     Are There General Protocol Parameters to Reduce Velocity Offsets? a Multi-Vendor Study.

Marijn P. Rolf¹, Mark B.M. Hofman¹, Peter D. Gatehouse², Karin Markenroth Bloch³, Martin J. Graves⁴, Albert C. van Rossum⁵, Philip Kilner², Rob M. Heethaar¹

¹Physics and Medical Technology, ICaR-VU, VU University Medical Center, Amsterdam, Netherlands; ²Cardiovascular Magnetic Resonance Unit, Royal Brompton Hospital, London, United Kingdom; ³Philips Healthcare, Lund University Hospital, Lund, Sweden; ⁴Department of Radiology, Addenbrooke's Hospital, Cambridge, United Kingdom; ⁵Department of Cardiology, ICaR-VU, VU University Medical Center, Amsterdam, Netherlands

Velocity offsets are of great concern for accuracy in cardiovascular flow quantification measurements. General protocol parameters (gradient speed, read-out bandwidth, partial echo, venc, and slice thickness) were studied across several MR-scanners of different vendors to investigate whether there is a general rule by which volume flow quantification protocols can be optimized in order to reduce velocity offsets. Gradient speed and partial echo showed a clear effect on the velocity offsets but not across all vendors. Slice orientation was found to be of major influence across all scanners, oblique slices generally gave higher offsets.

                  1338.     Optimal Bipolar Gradient Design to Reduce Velocity Offsets.

Marijn P. Rolf¹, Mark B.M. Hofman¹, Peter D. Gatehouse², Albert C. van Rossum³, Rob M. Heethaar¹

¹Physics and Medical Technology, ICaR-VU, VU University Medical Center, Amsterdam, Netherlands; ²Cardiovascular Magnetic Resonance Unit, Royal Brompton Hospital, London, United Kingdom; ³Department of Cardiology, ICaR-VU, VU University Medical Center, Amsterdam, Netherlands

Uncompensated eddy-currents cause velocity offsets, resulting in significant errors in clinical flow quantification. To reduce these offsets, the influence of velocity encoding gradient settings was studied in detail. Specifically the bipolar gradient timing, velocity encoding strategy (asymmetric or symmetric), and gradient amplitude and slew rate were studied. Timing showed no correlation with offset. Symmetrical encoding resulted in significantly lower offsets. Velocity offsets were also reduced by lowering the gradient amplitude and slew rate, however those protocols are not always compatible with the time-constraints of breath-hold imaging.

                  1339.     Nontriggered Cartesian Steady-State Free Precession Phase-Contrast MR

Joshua FP van Amerom¹, Michael S. Jansz¹, Christopher K. Macgowan¹

¹Departments of Medical Biophysics and Medical Imaging, University of Toronto and Hospital for Sick Children, Toronto, Ontario, Canada

Steady state free precession phase-contrast (PC-SSFP) is proposed for measurement of nontriggered time-averaged velocity as it exhibits less signal variation over the cardiac cycle than conventional PC-MR. It is shown that Cartesian nontriggered PC-SSFP provides an accurate mean-velocity measurement while conventional nontriggered PC-MR overestimates the mean velocity due to in-flow effects.

                  1340.     Investigation of Impact of Different Lung Pressures on Phasic Temporal Flow Profiles, Harmonic Content and Blood Flow of the Right Coronary Artery Measured Using PC-MRI

John James Totman^1,2, René M. Botnar³, Penny A. Gowland⁴, Andrea J. Wiethoff^3,5

¹King’s College London BHF Centre, Division of Imaging Sciences, NIHR  Biomedical Research Centre at , London, United Kingdom; ²Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingah, United Kingdom; ³King’s College London BHF Centre, Division of Imaging Sciences, NIHR  Biomedical Research Centre at, London, United Kingdom; ⁴Sir Peter Mansfield Magnetic Resonance Centre, University of Nottingham, Nottingham, United Kingdom; ⁵Philips Healthcare, Best, Netherlands

This study describes the phasic temporal flow profiles of blood flow of the RCA as measured at different specific lung pressures. Mathematical modelling was able to identify significant changes in phasic temporal flow profiles when no statistically significant differences in flow where detected. Clinically relevant additional information may be gained by using higher temporal and spatial PC-MRI blood flow measurements of the RCA as progressively more information is identified within the phasic temporal flow profiles of blood flow.

                  1341.     Whole Heart Flow Sensitive 4D MRI in Congenital Heart Disease

Julia Geiger¹, Raoul Arnold², Alex Frydrychowicz³, Brigitte Stiller², Mathias Langer¹, Michael Markl¹

¹Diagnostic Radiology and Medical Physics, University Hospital Freiburg, Freiburg, Baden-Wuerttemberg, Germany; ²Pediatric Cardiology, University Hospital Freiburg; ³Diagnostic Radiology , University of Wisconsin

The aim of this study was to assess the vessel morphology and altered hemodynamics in patients with operated congenital heart disease by flow sensitive whole heart 4D MRI. 15 patients with heterogeneous heart defects were examined on 1.5 or 3 T MRI scanners using a gradient echo sequence with interleaved 3-directional velocity encoding. Postoperative altered hemodynamics including flow acceleration or vortex formation could be visualized and characterized. Therefore, we take the method to be a promising modality for acquisition of comprehensive flow behavior and better understanding of extraordinary flow profiles in congenital heart disease.

                  1342.     Simulation of Phase-Contrast MRI Intravoxel Velocity Standard Deviation (IVSD) Mapping

Sven Petersson¹, Petter Dyverfeldt¹, Roland Gårdhagen¹, Matts Karlsson¹, Tino Ebbers¹

¹Linköping University and Center for Medical Image Science and Visualization (CMIV), Linköping, Sweden

Disturbed blood flow, characterized by velocity fluctuations, accompanies many cardiovascular diseases. PC-MRI intravoxel velocity standard deviation (IVSD) mapping permits the quantification of the intensity of these velocity fluctuations; turbulence intensity. Here, a PC-MRI IVSD measurement in stenotic flow was simulated using computational fluid dynamics (CFD) data obtained by large eddy simulations. The PC-MRI simulation showed overall strong similarities the CFD simulation and in-vitro measurement. The simulation of PC-MRI of fluctuating flow may facilitate controlled studies of the effects of velocity fluctuations on the PC-MRI signal and the optimization of IVSD mapping.

                  1343.     Reducing the Scan Time of Time-Resolved, 3D Phase Contrast Imaging with 2D Autocalibrated Parallel Imaging

Marcus T. Alley¹, Philip J. Beatty², Albert Hsiao¹, Shreyas S. Vasanawala¹

¹Radiology, Stanford University, Stanford, CA, United States; ²MR Applied Science Lab, GE Healthcare, Menlo Park, CA, United States

Time-resolved 3-dimensional phase-contrast MR imaging (3D-PC MRI) has developed as an active area of research for vascular imaging.  In general however the clinical adoption of this approach for routine vascular imaging has been hampered by the long acquisition times inherent in the technique (on the order of 10-20 minutes).  Several groups have addressed this issue by using parallel imaging to accelerate data acquisition in one dimension, and in this work we demonstrate the ability to perform auto-calibrated parallel imaging in both the in-plane and slice directions to reduce the overall scan time to the order of several minutes.

                  1344.     Reproducibility of Pulse Wave Velocity Measurements with Phase Contrast Magnetic Resonance and Applanation Tonometry

Jonathan D. Suever¹, David Huneycutt², Enrique Rojas-Campos³, Francesca Cardarelli³, Sam Fielden², Arthur Stillman, ^2,3, Paolo Raggi³, John N. Oshinski, ¹²

¹Biomedical Engineering, Georgia Institute of Technology / Emory University, Atlanta, GA, United States; ²Radiology, Emory University School of Medicine, Atlanta, GA, United States; ³Cardiology, Emory University School of Medicine, Atlanta, GA, United States

Increased aortic pulse wave velocity (PWV) due to arterial stiffening is commonly seen in patients with hypertension. Clinically, applanation tonomtery is used to measure PWV; however, we have developed a new method that uses PCMR combined with cross-correlation analysis. The purpose of this study was to compare the reproducibility of cross-correlation and applanation tonometry in normals and patients. In normal volunteers, the reproducibility of cross-correlation technique was better than applanation tonometry. In patients, cross-correlation and applanation tonometry measurements were not statistically different.

                  1345.     Quantification of Pre-Systolic Left Ventricular 4D Blood Flow Organization in Normal and Failing Hearts

Jonatan Eriksson¹, Petter Dyverfeldt¹, Jan Engvall¹, Ann F. Bolger², Tino Ebbers¹, Carl-Johan Carlhäll¹

¹Linköping University and Center for Medical Image Science and Visualization (CMIV), Linköping, Sweden; ²University of California San Francisco, San Francisco, CA, United States

Multidimensional patterns of intracardiac blood flow remain poorly characterized in health and disease. An extended pathline based left ventricular (LV) 4D blood flow quantification approach is presented. Three-directional, three-dimensional cine phase-contrast MRI data was acquired in healthy subjects and patients with idiopathic dilated cardiomyopathy and analyzed for assessment of the pre-systolic LV blood flow organization, in order to evaluate the preparation of different flow components for systolic outflow. Quantification of pre-systolic orientation may reflect an aspect of ventricular systolic efficiency that is impacted by flow-specific organization inside the diastolic ventricle.

                  1346.     Aortic Pulse Pressure Evaluation Using Fourier Velocity Encoded MR M-Mode

Valentina Taviani¹, Stacey S. Hickson², Christopher J. Hardy³, Andrew James Patterson¹, Victoria E. Young¹, Mark Butlin⁴, Carmel M. McEniery², Ian B. Wilkinson², Jonathan Harvey Gillard¹, Martin J. Graves¹

¹Department of Radiology, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom; ²Clinical Pharmacology Unit, University of Cambridge, Addenbrooke's Hospital, Cambridge, United Kingdom; ³GE Global Research, Niskayuna, NY, United States; ⁴The Australian School of Advanced Medicine, Macquarie University, Sydney, Australia

Central pulse pressure (PP) is a major determinant of ventricular afterload which can be accurately measured only by means of invasive pressure measurements. In this work, we present a method based on Fourier velocity encoded M-mode and the cross-section-averaged flow equations to estimate the local PP in the aorta. The obtained results were found to be in good agreement with applanation tonometry performed in a cohort of 18 healthy volunteers (bias=1.25mmHg, 95% limits of agreement (LOA) = [-5.7,8.2]mmHg) and intravascular pressure measurements obtained in 4 patients undergoing diagnostic catheterization ((bias=-0.37mmHg, 95% LOA = [-9.2,8.4]).

                  1347.     Association of Wall Compliance with Intraluminal Thrombus, Calcification, and the Size of Infrarenal Abdominal Aortic Aneurysm: An in Vivo MR Phase-Contrast Angiography Study

Hong Ye¹, Gador Canton², Xihai Zhao², William Kerwin², Chun Yuan², Zhanming Fan¹

¹Department, Beijing Anzhen hospital, Capital Medical University, Beijing, China; ²Radiology, University of Washington, Seattle, WA, United States

AAA rupture related risk factors include maximum diameter, wall stress or compliance, intraluminal thrombus (ILT), and calcification. The assessment of the correlations among these factors may improve the management and prognosis of AAA. This study investigated the association of wall compliance with ILT, calcification, and the size of infrarenal AAA using in vivo PC-MRA in 48 patients. We found the wall compliance was positively associated with ILT, which suggests thrombus may be a protective factor for AAA rupture. In addition, our results indicate that length to maximum diameter ratio may be a stronger indicator for wall compliance.

                  1348.     Contribution of the Blood Flow Evaluation by MRI in the Ascending Thoracic Aorta in Patients at Risk

Alain Lalande^1,2, Clotilde Billard-Philip², Marie Xavier¹, Olivier Bouchot^1,2, Eric Steinmetz², Alexandre Cochet¹, Paul Michael Walker^1,2, Jean-Eric Wolf^1,2, François Brunotte^1,2

¹LE2I, University of Burgundy, Dijon, France; ²University Hospital of Dijon, Dijon, France

Currently the evaluation of risk of rupture or dissection of the thoracic aorta is based on the aortic diameter, which is not a relevant parameter. To evaluate functional properties of the aorta, maximum blood flow velocity was evaluated in patients with well-classified diseases. 3D velocity imaging, acquired with velocity-encoded cine-MRI, and analysed with automatic post-processing allows the study of aortic blood flow. Compared with healthy subjects, the maximum blood flow velocity was higher for patients with bicuspid valve and lower for patients with the MYH11 mutation. There was no significant difference in patients with Marfan syndrome or annulo-aortic ectasia.

                  1349.     Flow Sensitive 4D MRI at 1.5T and 3T

Christoph Strecker¹, Andreas Harloff², Michael Markl³

¹Department of Neurology, University Hospital, Albert-Ludwigs-University , Freiburg, Germany; ²Department of Neurology, University Hospital, Albert-Ludwigs-University , Freiburg , Germany; ³Department of Radiology, Medical Physics, University Hospital, Albert-Ludwigs-University , Freiburg, Germany

Synopsis: It was the purpose of this study to evaluate the performance of flow-sensitive 4D MRI of the thoracic aorta at 1.5T and 3T. 10 healthy volunteers were examined with 4D-MRI at both field strengths with regard to velocity noise, 3D flow visualization and quantitative flow analysis. 3T was superior regarding reduced velocity noise, improved quality of blood flow visualization, and quantification of peak velocities. It could be shown that flow-sensitive 4D-MRI was feasible at both field strengths and can provide comprehensive information of aortic 3D hemodynamics and geometry.

                  1350.     Reproducibility of Semi-Automated Measurement for Carotid Arterial Distensibility Using CINE MRI at 3T

Gador Canton¹, Jinnan Wang², Li Dong¹, William Sean Kerwin¹, Chun Yuan¹

¹Radiology, University of Washington, Seattle, WA, United States; ²Clinical Sites Research Program, Philips Research North America, Briarcliff Manor, NY, United States

The aim of this study was to determine the inter-scan reproducibility of distensibility measurements at the common and internal carotid arteries using CINE MRI at 3 T. Our results show a good agreement in the area and the distensibility measurements between the two scans. Furthermore, we compared the difference in distensibility for both segments of the artery. We found a significant difference between the common and internal carotid arteries, suggesting that mechanical modeling of the forces acting on the arterial wall could be further improved by incorporating the different mechanical properties of different arterial segments.

                  1351.     Comparing Wall Shear Stress Measurements in the Descending Aorta Using Different Velocity Encoding Values

Larry Hernandez¹, Andrew L. Wentland^1,2, Erik T. Bieging², Chris J. Francois², Oliver Wieben¹

¹Medical Physics, University of Wisconsin, School of Medicine & Public Health, Madison, WI, United States; ²Radiology, University of Wisconsin, School of Medicine & Public Health, Madison, WI, United States

While studies have shown that high wall shear stress (WSS) creates aneurysms and low WSS contributes to aneurysmal growth, the downstream effects of an aneurysm on WSS remain unknown. In this study we compared measurements of peak WSS in the descending aorta of volunteers and in patients with an ascending aortic aneurysm. Measurements of peak WSS were lower in patients than in normal volunteers; the percent increase in WSS from diastolic baseline to peak systole was greater in volunteers than in patients. The long-term effects of lower WSS in the patients require further investigation.

                  1352.     Pressure Gradient Estimation from PC-MRI: Acceleration Versus Velocity Encoding

Jelena Bock¹, Felix Staehle¹, Ramona Lorenz¹, Kevin Michael Johnson², Juergen Hennig¹, Michael Markl¹

¹Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany; ²University of Wisconsin, Madison, United States

MRI can be used to estimate blood pressure gradients non-invasively by solving the Navier-Stokes equation. Most applications use velocity encoded MRI data to calculate pressure gradients by deriving local acceleration based on spatial and temporal derivates of the measured velocities. To minimize noise propagation errors, acceleration encoded MRI can be used to directly measure flow acceleration. In this study in-vitro and in-vivo data were used to systematically evaluate the performance of acceleration and velocity encoding PC-MRI for pressure gradient estimation. Results indicate that data derived from acceleration encoded MRI are less noisy and may provide more reliable pressure difference estimation.

                  1353.     Waveform Optimized (Easy to Build) Pulsatile Flow Phantom of the Common Carotid Artery

Clemens Diwoky¹, Christian Binter¹, Johannes Konrad Strasser¹, Rudolf Stollberger¹

¹Institute of Medical Engineering, Graz University of Technology, Graz, Austria

A phantom simulating the exact flow-velocity pulse shape within the common carotid artery is proposed. Beside the exact representation of the flow profile attention is paid on keeping the system flexible, simple and inexpensive. Parameters of the used components are figured out in order to optimize and manipulate the final pulsatile flow.

                  1354.     MRI Measurements of Wall Shear Stress in the Descending Aorta Downstream of an Ascending Aortic Aneurysm

Andrew L. Wentland^1,2, Erik T. Bieging², Alex Frydrychowicz², Thomas M. Grist^1,2, Oliver Wieben¹, Chris J. Francois²

¹Medical Physics, University of Wisconsin School of Medicine & Public Health, Madison, WI, United States; ²Radiology, University of Wisconsin School of Medicine & Public Health, Madison, WI, United States

While studies have shown that high wall shear stress (WSS) creates aneurysms and low WSS contributes to aneurysmal growth, the downstream effects of an aneurysm on WSS remain unknown. In this study we compared measurements of peak WSS in the descending aorta of volunteers and in patients with an ascending aortic aneurysm. Measurements of peak WSS were lower in patients than in normal volunteers; the percent increase in WSS from diastolic baseline to peak systole was greater in volunteers than in patients. The long-term effects of lower WSS in the patients require further investigation.

                  1355.     MRI Measurements of Wall Shear Stress in the Infrarenal Aorta in the Young and Old

Andrew L. Wentland¹, Erik T. Bieging², Alex Frydrychowicz², Mark L. Schiebler², Thomas M. Grist¹, Oliver Wieben¹, Chris J. Francois²

¹Medical Physics, University of Wisconsin School of Medicine & Public Health, Madison, WI, United States; ²Radiology, University of Wisconsin School of Medicine & Public Health, Madison, WI, United States

While studies have shown that low wall shear stress (WSS) contributes to the formation of atherosclerotic plaques and that low WSS correlates with high atherosclerotic indices, WSS in the elderly, who have a greater incidence of atherosclerosis, remains unknown. In this study, we compared measurements of peak WSS in the infrarenal aorta in young and old subjects. Measurements of peak WSS tended to be lower in the old than the young, although this trend was not statistically significant. The percent increase in WSS from diastolic baseline to peak systole was not significantly different between young and old subjects.

                  1356.     Evaluation of the Coherence of Local Indices of Aortic Stiffness Calculated from Magnetic Resonance Data Using a Theoretical Model Derived from the Moens-Korteweg Equation

Anas Dogui¹, Nadjia Kachenoura², Alain De Cesare², Muriel Lefort¹, Mourad Bensalah^1,3, Alain Herment¹, Boutouyrie Pierre^4,5, Elie Mousseaux^1,6

¹INSERM U678 ,UPMC, Paris, France; ²INSERM U678,UPMC, Paris, France; ³Radiology department, APHP, European Hospital Georges Pompidou,, Paris, France; ⁴INSERM U970, Paris, France; ⁵Pharmacology department, APHP, European Hospital Georges Pompidou, Paris, France; ⁶Radiology department, APHP, European Hospital Georges Pompidou, Paris, France

Aortic stiffness indices such as the local aortic deformability (AD) and the regional aortic pulse wave velocity (PWV) were assessed directly and non-invasively from morphological and hemodynamic magnetic resonance data on 40 subjects.  The consistency of these indices was well described by a theoretical model derived from the Moens-Korteweg equation. A global aortic deformability (ADe) was estimated from PWV and carotid pulse pressure using the theoretical model and gave a similar description of stiffness of the ascending aorta as the local AD.

                  1357.     Wall Shear Stress Analysis in Ascending Aortic Aneurysms Using PC VIPR

Erik Tierney Bieging¹, Benjamin R. Landgraf¹, Alex Frydrychowicz¹, Kevin M. Johnson², Oliver Wieben, ¹², Christopher J. Francois¹

¹Radiology, University of Wisconsin - Madison, Madison, WI, United States; ²Medical Physics, University of Wisconsin - Madison, Madison, WI, United States

Wall shear stress (WSS) was analyzed in patients with ascending aortic aneurysms (AscAA) using phase-contrast MRI with 3D radial undersampling (PC VIPR), a 4D flow technique.  Time resolved WSS was compared between patients with AscAA and healthy volunteers with normal aortic anatomy.  Patients with AscAA were shown to have increased diastolic WSS, decreased WSS change over the cardiac cycle, and slower onset of systolic WSS.  Additionally, spatial changes in WSS in AscAA were demonstrated.

                  1358.     Quantification of Left and Right Ventricular Kinetic Energy Using Four Dimensional Intracardiac Magnetic Resonance Imaging Flow Measurements

Marcus Carlsson¹, Einar Heiberg¹, Johannes Töger¹, Karin Markenroth², Freddy Ståhlberg³, Håkan Arheden¹

¹Clinical Physiology, Lund University Hospital, Lund, Skane, Sweden; ²Philips Medical Systems, Lund University Hospital, Lund, Skane, Sweden; ³Radiation Physics, Lund University Hospital, Lund, Skane, Sweden

This study has demonstrated the feasibility of a new method for non-invasive quantification of biventricular kinetic energy using 4D phase contrast velocity encoded CMR. Three energy peaks of the LV and RV were seen in healthy subjects. Interestingly, the systolic energy was higher in the RV compared to the LV and in contrast the energy during early diastole was higher in the LV compared to the RV.

                  1359.     A Novel MRI Framework for the Quantification of Any Moment of Arbitrary Velocity Distributions

Petter Dyverfeldt¹, Andreas Sigfridsson¹, Hans Knutsson¹, Tino Ebbers¹

¹Linköping University and Center for Medical Image Science and Visualization (CMIV), Linköping, Sweden

Under the assumption that the intravoxel velocity distribution is symmetric about its mean, the well-known MRI phase-difference method permits an estimation of the mean velocity of a voxel. The mean velocity corresponds to the first moment of the velocity distribution. Here, a novel framework for the quantification of any moment of arbitrary spin velocity distributions is presented. Simulations on realistic velocity distributions demonstrate its application. The presented moment framework may assist in improving the understanding of existing MRI methods for the quantification of flow and motion and serve as a basis for the development of new methods.

                  1360.     Is 2-D  Velocity Encoded Cardiac MRI Accurate at 3T?

Lindsay Marie Zeeb¹, Jeffrey Kaye, Curtis E. Green¹, Trevor J. Andrews, George Ernest Gentchos¹

¹Radiology, University of Vermont, Burlington, VT, United States

2-D Velocity encoded MRI (VEC-MRI) has not been widely validated at 3T field strength with regard to optimal imaging parameters and overall accuracy.  In this study, 2D VEC-MRI at 3T was tested in vivo over a wide range of imaging parameters and compared to well validated cine functional volumes.   VEC-MRI was highly accurate over a wide range of velocity encoded values, orientation of flow and at varying spatial resolution.  This suggests that 2D VEC-MRI is highly accurate at 3T field strength and that further efforts to increase signal to noise or spatial resolution are probably not necessary compared to 1.5 T.

                  1361.     4D Blood Flow in the Left Heart

Daniela Foell¹, Steffen Taeger², Bernd Jung³, Jelena Bock³, Philipp Blanke³, Christoph Bode², Michael Markl³

¹Cardiology , University Hospital , Freiburg, Germany; ²Cardiology, University Hospital, Freiburg, Germany; ³Diagnostic Radiology/Medical Physics, University Hospital, Freiburg, Germany

Flow-sensitive 4D MRI was performed to visualize the complex blood flow in the left ventricle (LV), atrium and out-flow tract. Left atrial and LV vortex formation was seen in older and younger volunteers. The left pulmonary veins promote more pronounced vortexes in older and younger volunteers during systole and diastole. Intraventricular vortex formation was not different between older and younger individuals with most vortexes located in basal and midventricular parts of the LV. The knowledge of blood flow in the healthy heart is essential for further patient studies in cardiac disease such as LV aneurysms, valve insufficiencies or atrial arrhythmia.

                  1362.     Acquisition of Velocity-Encoded CMR Is Feasible in Presence of Contrast Agent, But Delineation for Strain Is Difficult

Erik Hedstrom¹, Erik Bergvall¹, Karin Markenroth Bloch^2,3, Freddy Stahlberg^4,5, Hakan Arheden¹

¹Cardiac MR Group, Department of Clinical Physiology, Lund University and Lund University Hospital, Lund, Sweden; ²MR department, Lund University Hospital, Lund, Sweden; ³Philips Medical Systems, Best, Netherlands; ⁴Department of Medical Radiation Physics, Lund University, Lund, Sweden; ⁵Department of Radiology, Lund University Hospital, Lund, Sweden

AIM: We sought to determine whether the presence of contrast agent affects PC-CMR measurements of aortic blood flow, and myocardial displacement of the left ventricle in humans. METHODS: Velocity-encoded data was acquired pre and post contrast agent administration. RESULTS: Cardiac output differed -0.04±0.52 l/min and myocardial displacement 0.1±0.5mm. Magnitude image contrast for myocardial displacement was visually lower in the post contrast agent images. CONCLUSIONS: Acquisition of aortic flow is feasible both in the absence and presence of contrast agent. For myocardial displacement phase-contrast data is assessable as such, but delineation not possible post contrast agent administration due to lower image contrast.

                  1363.     Magnetic Resonance 2D Phase Contrast Flow Imaging of Patients with Stenotic Aortic and Pulmonary Valves

Juha Ilmari Peltonen^1,2, Touko Kaasalainen^3,4, Sari Kivistö³, Miia Holmström³, Kirsi Lauerma¹

¹HUS Medical Imaging Center, Helsinki University Central Hospital, Helsinki, Finland; ²Department of Biomedical Engineering and Computational Science, Aalto University, Helsinki, Finland; ³HUS Medical Imaging Center, Helsinki University Central Hospital, N/A, Helsinki, Finland; ⁴Department of Physics, Helsinki University, Helsinki, Finland

2D through plane phase contrast imaging of patients with stenotic pulmonal or aortic valves is subject to many sources of error. Accelerated flow speed increases the amount and range of the acceleration artefact near the valve. On the other hand, the nature of the flow becomes highly turbulent soon after the valve. In this study we have examined the effect of the mentioned error sources to measured net flow. Also, the optimal position of the measurement plane and clinical routine currently in use is discussed.

                  1364.     Validation of 4D Left Ventricular Blood Flow Assessment Using Pathlines

Jonatan Eriksson¹, Petter Dyverfeldt¹, Jan Engvall¹, Ann F. Bolger², Carl-Johan Carlhäll¹, Tino Ebbers¹

¹Linköping University and Center for Medical Image Science and Visualization (CMIV), Linköping, Sweden; ²University of California San Francisco, San Francisco, CA, United States

A validation study of a pathline based left ventricular (LV) blood flow quantification approach is presented. The approach integrates morphological and three-directional, three-dimensional cine phase-contrast MRI flow data, to separate the blood that transits the LV into four components. The validation includes comparison of the LV outflow obtained from this approach to results from clinically applied methods of determining LV outflow: 2D through-plane cine PC-MRI and Doppler ultrasound. Additionally inflow and outflow volumes obtained from the pathline based approach were compared.

                  1365.     Blood Flow Patterns in the Left Ventricle of the Healthy Human Heart Described by Lagrangian Coherent Structures Computed from 4D Phase Contrast MRI

Johannes Töger^1,2, Johannes Ulén^1,3, Marcus Carlsson¹, Gustaf Söderlind², Håkan Arheden¹, Einar Heiberg¹

¹Cardiac MR Group, Department of Clinical Physiology, Lund University Hospital, Lund, Sweden; ²Numerical Analysis, Centre for Mathematical Sciences, Lund University, Lund, Sweden; ³Mathematical Imaging Group, Centre for Mathematical Sciences, Lund University, Lund, Sweden

Blood flow patterns in the human heart are important for our understanding of cardiac pumping, and 4D phase contrast MRI may provide new insights. However, the flow is complex, making it hard to visualize and understand. In this work, the flow patterns in the left ventricle are interpreted using Lagrangian Coherent Structures, which reveal dynamically distinct compartments in the flow. Specifically, the inflow into the left ventricle is described in four healthy volunteers.

                  1366.     Volumetric, 3D Velocity Encoded Valve Imaging with Radial Undersampling

Steven R. Kecskemeti¹, Kevin Johnson¹, Oliver Wieben¹

¹Medical Physics, University of Wisconsin, Maidson, WI, United States

The application of PC to cardiac valve imaging offers unique challenges.   With the valve location changing as much as 30mm within the cardiac cycle, 2D single directional PC exams may miss the intended location.  An attractive alternative is 3D PC covering a modest slab, with three directional velocity encoding [1].   However, current use is hampered by long scantimes necessary to achieve the high spatial and temporal resolution required for valve imaging.   A 3D hybrid radial k-space acquisition allows both the mitral and tricuspid or the pulmonary and aortic valves to be imaged in a single scan within a reasonable time.

                  1367.     Inline Magnitude of Velocity Calculation for Phase Contrast MRA Improves Cardiac Valvular Assessment

Philip Anthony Hodnett^1,2, Jeremy D. Collins³, Timothy Scanlon, Amir H. Davarpanah, Peter Weale⁴, Sven Zuehlsdorff⁴, James C. Carr, Chris Glielmi⁴

¹Department of Cardiovascular Imaging, Northwestern University, Chicago, IL, United States; ²Northshore University HealthCare System, Chicago, IL, United States; ³Northwestern University, United States; ⁴Siemens Healthcare, MR Research and Development, Chicago, IL

Background: Standard phase contrast MRI (PC-MRI) has potential sources for error when used in assessment of cardiac valvular pathology. We propose a new directionally independent tool for peak velocity evaluation  Methods:The technique employs a phase contrast sequence with three flow encoding directions and one flow compensated reference. Phase difference images between between each flow encoded and the flow compensated images were quantified for directional velocity Results: The root sum of square of the 3D encoded data is computed inline and displayed in a magnitude of velocity dataset for each patient. We compared standard Throughplane phase contrast MRA and Inline calculation velocity of magnitude to the reference standard echocardiography. Conclusion:Extracting the magnitude of peak velocity independent of its direction significantly reduces error in peak velocity estimation (one-tailed t-test:p<0.02)

                  1368.     In-Vitro Validation of Phase Contrast MRI in a Stenotic Phantom Under Steady Flow Using PIV

Iman Khodarahmi¹, Mostafa Shakeri, ¹², Ron Pratt³, Janaka Wansapura³, Michael Keith Sharp², Amir Arsham Amini¹

¹Department of Electrical and Computer Engineering, University of Louisville, Louisville, KY, United States; ²Department of Mechanical Engineering, University of Louisville, Louisville, KY, United States; ³Imaging Research Center, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH, United States

Phase Contrast MRI (PC-MRI) can be used to measure velocities in fluid flow using the phase mapping of the moving spins. Phase velocity mapping technique assumes that the velocity is constant over the echo time. This assumption is not valid for accelerating spins. In this study, we sought to evaluate the accuracy of PC-MRI velocity field in a severe stenotic phantom model, where the convective component of the acceleration is large. Considering the Particle Image Velocimetry (PIV) technique as the gold standard, we observed errors up to 26%, 16%, and 42% for pre-stenosis, at the stenosis, and post-stenosis regions, respectively.

                  1369.     Inline Directionally Independent Magnitude of Velocity Maps for Visualization and Quantification of Jet Flow

Jie Deng¹, Christopher Glielmi², Peter Weale², Cynthia Rigsby¹, Andrew deFreitas³, Sven Zuehlsdorff²

¹Radiology, Children's Memorial Hospital, Chicago, IL, United States; ²Siemens Healthcare; ³Cardiology, Children's Memorial Hospital, Chicago, IL, United States

Pediatric patients with congenital heart diseases often have irregular blood flow patterns (jet flow) with variant orientation and distributions. Phase contrast MRI with velocity encoding provides flow visualization and quantification of peak velocity within the core of jet flow. 2D slice oriented orthogonal to jet flow with through-plane velocity-encoding is commonly used in clinical studies. However, post-stenotic jets frequently exhibit a degree of eccentricity and can change direction throughout the cardiac cycle. Irregular and narrow jets can be more difficult to be measured. We propose inline computation of velocity magnitude independent of direction, eliminating reliance on optimal slice orientation and facilitating clinical evaluation of irregular flow patterns as found in stenotic jets.

                  1370.     Validation of Distensibility Measurements from MRI-Based Pulse Wave Velocity

Gabriel Acevedo-Bolton¹, James Leung¹, Chris Hardy², Craig DeVincent, David Saloner^1,3, Alison Meadows

¹Radiology, UCSF, San Francisco, CA, United States; ²GE Global Research, Niskayuna, NY, United States; ³Radiology, VA Medical Center, San Francisco, CA

A one-dimensional Fourier Velocity Encoded MRI method was used to measure the Pulse Wave Velocity in a series of elastic tubes with differing elasticity.  The distensibility of these tubes was also measured using mechanical testing.  Good correlation was found between the distensibility measured by mechanical testing methods compared to that estimated from the MR velocimetry technique.  This study provides confidence that MRV is a useful technique for determining the Pulse Wave Velocity in compliant vessels and could be used for assessing differing stages of vascular disease.

                  1371.     Analysis of Flow in Artificial Stenosis Models of Mid-Sized Arteries Using 3D PC-MRI

Frank G. Zöllner¹, Stefan Scheuer^1,2, Erik Tumat¹, Lothar R. Schad¹

¹Computer Assisted Clinical Medicine, Heidelberg University, Mannheim, Germany; ²Chair for Applied Physics and Center for NanoScience, Ludwig-Maximilians-University Munich, Munich, Germany

The aim of this work was to investigate whether 3D PC-MRI could be applied to support the grading of stenosis in med-sized arteries. Using a specially constructed flow phantom and a stenosis model with tube diameter of 8 mm and a stenosis of 50%, experiments at different flow rates (180 - 640 ml/s), slice thickness (1 – 4 mm), field strength (1.5 and 3.0 T) were performed. Results show that examinations should be performed at high field (3.0 T) and at flow rates up to 500 ml/min without hampering the measurements by areas of signal loss. 3D PC-MRI of mid-sized vessels with stenosis is feasible for certain flow rates. The presented results could be seen as guidance for in vivo situations to assess if an examination of a patient is reasonable in terms of outcome.

                  1372.     MR-Based Imaging for Patient Specific, Fully Coupled 2-Way Fluid-Structure Interaction of the Human Aorta

Jonas Lantz¹, Johan Renner¹, Matts Karlsson¹

¹Department of Management and Engineering, Linköping University, Linköping, Sweden

A method of incorporating MR-based imaging with advanced fluid-structure interaction simulations of the human aorta is presented. It is well established that wall shear stress is an indicator of increased risk for development of atherosclerotic plaques, and to be able to more accurately capture the flow (and solid) dynamics of the aorta, the movement of the wall is computed based on the blood flow. The geometries are extracted with a MRI scanner together with flow velocities, and used as boundary conditions in the simulations. The feasibility of the method is shown and initial results looks very promising.

MRA Human/Clinical Studies

                  1373.     Reduction of the RF Shielding Caused by a Vascular Stent Using a Pseudo-Adiabatic Excitation

Guillaume Gilbert¹, Gilles Beaudoin¹

¹Department of Radiology, Centre Hospitalier de l'Université de Montréal, Montreal, Quebec, Canada

The use of a pseudo-adiabatic excitation pulse is investigated as a way to reduce the radiofrequency shielding caused by a vascular stent and consequently improve the depiction of the vessel lumen inside the stent. Using measurements performed on a vascular phantom, the employment of a pseudo-adiabatic excitation pulse is shown to allow the same effective flip angle to be simultaneously obtained inside and outside the stent, therefore eliminating the radiofrequency shielding effect of the stent during excitation.

                  1374.     Improvements to NCE-MRA: Vascular Anatomy by Non-Enhanced Static Subtraction Angiography (VANESSA)

Andrew Nicholas Priest¹, Martin John Graves¹, David John Lomas¹

¹Radiology, Addenbrookes Hospital and University of Cambridge, Cambridge, United Kingdom

Non-contrast-enhanced MR angiography methods can avoid the constraints associated with a short (first pass) acquisition window and concerns over contrast agent safety. A recently demonstrated method uses a modified motion-sensitised driven equilibrium (MSDE) preparation to controllably suppress flowing blood. Vascular images are generated by subtraction of bright- and dark-blood images, obtained without and with flow suppression. This work demonstrates a series of modifications to improve image quality and background suppression, and evaluates the technical performance of the resulting method in the peripheral vasculature of 8 volunteers. Excellent image quality was obtained in all arteries, except for some popliteals.

                  1375.     Time-Resolved MR Angiography for Evaluation of Peripheral Congenital Vascular Lesions in Young Children

Gurpreet Singh Sandhu^1,2, Daniel P. Hsu¹, Joan Tamburro³, Mark A. Griswold¹, Vikas Gulani^1,2

¹Radiology, University Hospitals of Cleveland, Case Western Reserve University, Cleveland, OH, United States; ²Case Center for Imaging Research, Case Western Reserve University, Cleveland, OH, United States; ³Dermatology, University Hospitals of Cleveland, Case Western Reserve University, Cleveland, OH, United States

Digital subtraction angiography is considered the gold standard imaging technique for diagnosis and monitoring of pediatric peripheral vascular lesions since in addition to providing information regarding blood supply to the lesion, it also provides an option for therapeutic embolization. Unfortunately, this technique is an invasive procedure requiring induction of general anesthesia, iodinated contrast material, ionizing radiation exposure and small albeit definable risk of potentially life-threatening complications. Here, we evaluate the efficacy of time-resolved MRA for evaluation of suspected peripheral vascular lesions in infants and young children.

                  1376.     High Temporal and Spatial Resolution 3D CE-MRA of the Whole Brain

Clifton R. Haider¹, Josh Damon Trzasko¹, Eric A. Borisch¹, Norbert G. Campeau¹, Petrice M. Mostardi¹, John Huston¹, Armando Manduca¹, Stephen J. Riederer¹

¹Radiology, Mayo Clinic, Rochester, MN, United States

The purpose of this work is to demonstrate the implementation of a dynamic MRA technique using 12x 2D SENSE accelerated Cartesian Acquisition with Projection-Reconstruction-like sampling for angiographic imaging of the brain, with 1 sec frame time and 3 sec temporal footprint, sufficient to resolve arterio-venous transit of cerebral blood flow. Additional post-processing with a non-convex compressive sensing reconstruction is also presented, resulting in further improvement of angiographic image quality, from removal of non-uniform noise amplification.

                  1377.     T1 Contrast of MPRAGE in Carotid Plaque Imaging

Yiu-Cho Chung¹, Michael Jerosch-Herold², Ravi T. Seethamraju³, Peter Libby⁴, Marcelo Di Carli⁵, Raymond Kwong⁶

¹Siemens Medical Solutions USA, Inc., Columbus, OH, United States; ²Radiology, Brigham and Women's Hospital, MA, United States; ³Siemens Medical Solutions USA, Inc., MA, United States; ⁴Cardiovascular Medicine, Brigham and Women's Hospital, MA, United States; ⁵Nuclear Medicine, Brigham and Women's Hospital, MA, United States; ⁶Cardiovascular Imaging, Brigham and Women's Hospital, MA, United States

MPRAGE has excellent T1 contrast and is useful for thrombus imaging. Though blood is usually suppressed in vessel wall imaging, nonzero blood signal may be useful in depicting blood and vessel wall. By setting TI longer than the blood null time, MPRAGE can provide good contrast between blood and vessel wall due to their intrinsic T1 difference. In a small patient cohort, we used such approach for MPRAGE, and compared the images with T2w-SPACE. We found that the “grey blood” MPRAGE can provide information about the plaque and lumen that was not obvious in dark blood images.

                  1378.     Common Artifacts of Pulmonary Artery MRA and Potential Solutions

Scott K. Nagle^1,2, Mark L. Schiebler¹, Christopher J. Francois¹, Thomas M. Grist¹, Scott B. Reeder^1,3

¹Radiology, University of Wisconsin, Madison, WI, United States; ²Radiology, Wm. S. Middleton Veterans Affairs (VA) Hospital, Madison, WI, United States; ³Medical Physics, University of Wisconsin, Madison, WI, United States

Contrast-enhanced MRA has been clinically accepted at our institution as a useful alternative to CTA for the diagnosis of pulmonary embolism, particularly in young patients where radiation dose reduction is a high priority.  This increasing utilization has led to the need to understand and mitigate artifacts that are unique to MRA, increasing the diagnostic accuracy of these scans. Based upon our experience interpreting approximately 200 clinical cases, we have identified and provided potential solutions to two common artifacts that are unique to MRA.

                  1379.     Comparison of Non Contrast-Enhanced Balanced TFE and CE-MRA for Evaluation of Upper Extremity Vasculature Prior to Vascular Access Creation

Arie Simon Bode^1,2, Robrecht Nils Planken³, Bastiaan Versluis¹, Joachim E. Wildberger^1,4, Jan H. Tordoir^2,5, Tim Leiner^1,5

¹Radiology, Maastricht University Medical Center, Maastricht, Netherlands; ²Surgery, Maastricht University Medical Center, Maastricht, Netherlands; ³Radiology, Academic Medical Center, Amsterdam, Netherlands; ⁴Cardiovascular Research Institute Maastricht, Maastricht, , Netherlands; ⁵Cardiovascular Research Institute Maastricht, Maastricht, Netherlands

Knowledge of upper extremity vascular geometry prior to dialysis access creation improves clinical outcome. Purpose of the present study was to compare a non-contrast enhanced (NCE) balanced TFE sequence with the current standard of reference, CE-MRA. In 10 healthy volunteers and 5 patients with ESRD we obtained both NCE-bTFE and CE-MRA images. Although CE-MRA was superior for arterial depiction NCE-bTFE yielded images of diagnostic quality in the vast majority of subjects. Furthermore, NCE-bTFE enabled visualization of significantly more venous segments compared compared to CE-MRA. bTFE proved to be an attractive alternative for pre-operative vascular mapping prior to vascular access creation.

                  1380.     Multicenter Intraindividual Comparison of Gadobenate Dimeglumine and Gadofosveset Trisodium for MR Angiography of the Renal Arteries

Gunther Schneider¹, Mieczyslaw Pasowicz², Josef Vymazal³, Zdenek Seidl⁴, Manuela Aschauer⁵, Deniz Bilecen⁶, Roberto Iezzi⁷, Claudio E M Ballarati⁸

¹Radiology, University Hospital Hamburg, Hamburg/Saar, Germany; ²Diagnostics and Rehabilitation, John Paul II Hospital, Krakow, Poland; ³Radiology, Na Homolce Hospital, Prague, Czech Republic; ⁴Radiology, Lékarská Fakulta Neurologicka Klinika, Prague, Czech Republic; ⁵Medical University of Graz, Graz, Austria; ⁶Radiology, University Hospital Basel, Switzerland; ⁷Radiology, Università G. D'Annunzio, Chieti, Italy; ⁸Radiology, Hospital Valduce, Como, Italy

In a prospective comparison of the efficacy and safety of gadobenate dimeglumine vs the intravascular blood pool agent gadofosveset trisodium for contrast-enhanced MR angiography (CE-MRA) of the renal arteries in 38 subjects, blinded experts consistently found first-pass CE-MRA after gadobenate dimeglumine to be superior to CE-MRA after gadofosveset in terms of sensitivity, specificity, accuracy, PPV, and NPV. Steady state images obtained following gadofosveset administration provided no additional diagnostic benefit in this study.

                  1381.     Diagnostic Performance of Gadobenate Dimeglumine and Gadopentetate Dimeglumine for Peripheral MRA: Multicenter Comparison with DSA

Timothy Leiner¹, Suzanne C. Gerretsen², Thierry le Maire², Stephan Miller³, Siegfried Thurnher⁴, Christoph U. Herborn⁵, Henrik J. Michaely⁶, Harald Kramer⁷, Angelo Vanzulli⁸, Josef Vymazal⁹, Martin Wasser¹⁰

¹Radiology, Maastricht University Hospital, Maastrict, Netherlands; ²Radiology, Catharina Hospital, Eindhoven, Netherlands; ³Radiology, Eberhard-Karls University, Tübingen, Germany; ⁴Radiology, Hospital of St. John of God, Vienna, Austria; ⁵Radiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany; ⁶Institute of Clinical Radiology, University Hospital Mannheim, Mannheim, Germany; ⁷Radiology, Ludwig Maximilians University, Munich, Germany; ⁸Hospital Niguarda Ca’ Granda, Milan, Italy; ⁹Radiology, Na Homolce Hospital, Prague, Czech Republic; ¹⁰Radiology, Leiden University Medical Center, Leiden, Netherlands

Equivalent 0.1 mmol/kg doses of gadobenate dimeglumine and gadopentetate dimeglumine were compared in terms of diagnostic performance in 397 segments from 96 patients with suspected peripheral arterial occlusive disease undergoing CE-MRA, using DSA as the reference standard. Three blinded readers rated the diagnostic performance of gadobenate dimeglumine significantly better in terms of sensitivity, specificity, and overall accuracy. In addition, significantly higher PPV and NPV values were noted after gadobenate dimeglumine compared to gadopentetate dimeglumine, despite the equivalent dose.

                  1382.     Hemodynamic Assessment of the Splanchnic Arteries with Aneurismal Dilations Using Time-Resolved Three Dimensional Phase Contrast MRA (4Dflow)

Yasuo Takehara¹, Haruo Isoda², Shuhei Yamashita², Mika Kamiya², Naoki Unno³, Hiroyasu Takeda¹, Masaya Hirano⁴, Marcus T. Alley⁵, Roland Bammer⁵, Takashi Kosugi⁶, Yasuhide Ohkura⁶, Harumi Sakahara

¹Radiology, Hamamatsu Univ. Hospital, Hamamatsu, Shizuoka, Japan; ²Radiology, Hamamatsu Univ. School of Medicine, Hamamatsu, Shizuoka, Japan; ³Vascular Surgery, Hamamatsu Univ. School of Medicine; ⁴GE Healthcare, Hino, Tokyo, Japan; ⁵Radiology, Stanford Univ.; ⁶R's Tech Co. Ltd.

Combined use of time-resolved 3 dimensional phase contrast MRA (4D-flow) and flow analysis software was useful in planning the catheter and surgical intervention for the aneurismal dilation of the splanchnic arteries. The method identified the significant alteration in the flow dynamics in splanchnic arteries mostly due to celiac artery stenosis (73 %). Measured WSS of the segment of aneurismal wall was significantly lower ( < 1.5 Pa) than normal segments, which may be reflecting that the aneurismal wall is continuously affected by the growing risk of rupture.

                  1383.     Peripheral MRA Using an Interleaved Variable Density Cartesian Acquisition with HYPR Reconstruction

James H. Holmes¹, Kang Wang², Reed F. Busse¹, Christopher J. Francois³, Philip J. Beatty⁴, Lauren A. Keith², Yijing Wu², Scott B. Reeder³, Jean H. Brittain¹, Frank R. Korosec³

¹Applied Science Laboratory, GE Healthcare, Madison, WI, United States; ²Medical Physics, University of Wisconsin-Madison, Madison, WI, United States; ³Radiology, University of Wisconsin-Madison, Madison, WI, United States; ⁴Applied Science Laboratory, GE Healthcare, Menlo Park, CA

A method combining an interleaved variable density (IVD) Cartesian acquisition with a reconstruction that integrates HYPR and parallel imaging is applied to peripheral run-off MRA.  The method is compared to conventional view sharing in normal volunteers, demonstrating improved spatial resolution and temporal fidelity.  Preliminary clinical results in patients with peripheral vascular disease are also presented.

                  1384.     Quiescent Interval Single Shot MR Angiography

Robert R. Edelman¹, John Sheehan¹, Eugene Dunkle¹, James Carr², Christopher Glielmi³, Xiaoming Bi³, Ioannis Koktzoglou¹

¹Radiology, NorthShore University HealthSystem, Evanston, IL, United States; ²Northwestern University; ³Siemens Healthcare

Quiescent interval single shot (QISS) MRA uses an ECG-triggered, fat suppressed, 2D balanced SSFP sequence incorporating slice-selective saturation and a quiescent interval for maximal inflow enhancement.  Following optimization at 1.5 Tesla, a pilot study was performed in patients with peripheral vascular disease (PVD) using contrast-enhanced MRA as the reference standard.  The sensitivity, specificity, positive and negative predictive values of QISS for significant stenosis or occlusion were 92.2%, 94.9%, 83.9% and 97.7%.  In conclusion, QISS provided robust depiction of normal peripheral arterial anatomy and PVD in less than 10 minutes without the need to tailor the technique for individual patients.

                  1385.     Deep Venous Thrombosis: Diagnostic Value of Non-Contrast-Enhanced MR Venography Using Electrocardiography-Triggered Three-Dimensional Half-Fourier FSE

Atsushi Ono^1,2, Kenya Murase¹, Toshitaka Taniguchi³, Osamu Shibutani⁴, Satoru Takata², Yasuyuki Kobashi², Yusuke Hashiguchi², Mitsue Miyazaki^5,6

¹Medical Physics and Engineering, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan; ²Medical Technology, Kousei Hospital, Okayama, Japan; ³Kawasaki Medical School Kawasaki Hospital, Okayama, Japan; ⁴Kurashiki Riverside Hospital, Kurashiki, Okayama, Japan; ⁵Toshiba Medical Research Institute, Vernon Hills, IL, United States; ⁶Toshiba Medical Systems Corp, Otawara, Tochigi, Japan

The diagnostic accuracy of non-contrast-enhanced MR venography using both the flow-refocused fresh-blood imaging (FR-FBI) and the swap phase-encode arterial double-subtraction elimination (SPADE) techniques for detecting deep vein thrombosis (DVT) were prospectively assessed and  compared using conventional X-ray venography as the reference standard. Thirty-two consecutive patients suspected of having DVT, examined using conventional X-ray venography, underwent MR FR-FBI and SPADE. Two radiologists independently assessed the non-contrast MR venograms for presence and the sensitivities for diagnosing thrombus were 100% for both reviewers. The specificities were 100% and 99.6% and the interobserver agreement was almost perfect (ƒÈ = 0.92).

                  1386.     Aortic Compliance in Normals Correlates with Age and BMI

Yi Wang^1,2, Edwin Estrada¹, Simcha Pollack¹, Visali Kodali¹, Nathaniel Reichek^1,2

¹Research and Education, St. Francis Hospital, Roslyn, NY, United States; ²Biomedical Enginnering, State University of New York, Stony Brook, NY, United States

Aortic compliance (AC) can be evaluated noninvasively and its reduction with age in normals has been demonstrated with MRI. Decreased aortic compliance (AC) is associated with aging, systolic hypertension and left ventricular diastolic dysfunction. Aortic pulse wave velocity (PWV) often serves as a surrogate to AC, and it can be evaluated using a single breath-hold phase contrast imaging technique. Its age correlation has been demonstrated by both MR and echo studies in normal volunteers. We evaluated the aortic compliance and their relationship to age, as well as the other biomedical parameters in 189 normal volunteers.

                  1387.     Comparison of High Spatial Resolution Time-Resolved 3D Contrast-Enhanced MR Angiography

Phillip Matthew Young¹, James F. Glockner¹, Clifton R. Haider¹, Petrice M. Mostardi¹, Terri J. Vrtiska¹, Thanila A. Macedo¹, Stephen J. Riederer¹

¹Diagnostic Radiology, Mayo Clinic, Rochester, MN, United States

10 patients were imaged using both CTA and high-resolution time-resolved MRA and images were compared for evaluation of below the knee arterial runoff. Although the study population is skewed because some patients were referred for MRA because of nondiagnostic CTA, MRA was not limited by calcification, inadequate arterial opacification, or venous contamination, all of which were problematic with CTA.  Although SENSE reconstruction artifact was apparent on the MRA  images, it did not interfere with image interpretation.  Additionally, the time-resolved dataset acquired with MRA provided additional information about flow and perfusion which was not apparent with the CTA dataset.

                  1388.     Comprehensive Non-Contrast-Enhanced MRI of the Thoracic Aortic Dissection: Non-Contrast-Enhanced 3D MRA and Time-Resolved 3D Flow Tracking Techniques

Yasuo Amano¹, Ryo Takagi¹, Yuriko Suzuki², Testuro Sekine¹, Yoshio Matsumura¹, Katsuya Takahama¹, Shinichiro Kumita¹, Van Cauteren Marc²

¹Radiology, Nippon Medical School, Tokyo, Japan; ²Philips Electronics Japan, Tokyo, Japan

Non-contrast-enhanced 3D MRA acquired by turbo spin-echo or steady-state free precession depict thoracic aortic dissection, but it lacks in the flow information at the entry, ulcer-like projection, and true and false lumen. Time-resolved 3D flow tracking generated from 3D phase-contrast imaging provided the blood flow data and visualized the streamline or velocity vector in aortic dissection. The combination of unenhanced 3D MRA and time-resolved 3D flow tracking may be useful for the comprehensive evaluation of the thoracic aortic dissection.

                  1389.     MPRAGE Detection of Hemorrhage in Carotid Plaque

Joseph Scott McNally¹, Seong-Eun Kim², John Roberts², Daniel Nightingale³, Laura K. Findeiss, Gerald S. Treiman⁴, Dennis L. Parker²

¹Radiology, University of Utah, Salt Lake City, UT, United States; ²UCAIR, University of Utah; ³Pathology, VA Salt Lake City Health Care System; ⁴Surgery, VA Salt Lake City Health Care System

Plaque hemorrhage may discriminate an unstable plaque from a more stable lesion. Patients scheduled for carotid endarterectomy underwent MR imaging with 3D MPRAGE (Magnetization-prepared rapid acquisition with gradient-echo), 3D TOF, 2D DIR T1 and T2 sequences.  After carotid endarterectomy, plaque components were identified.  MPRAGE hyperintensity correlates with hemorrhage on histology.  Variable ages of blood products were detected by the MPRAGE sequence, ranging from recent to remote.  Hemorrhage was discriminated from lipid, necrosis, collagen, and calcification using the MPRAGE sequence.  This sequence may play an important role in determining which patients benefit from medical management as opposed to surgical intervention.

                  1390.     Benefits and Pitfalls in the Use of Contrast Agents in 4D Flow Imaging

Michael Loecher¹, Christopher Francois², Kevin Johnson¹, Darren Lum², Oliver Wieben^1,2

¹Department of Medical Physics, University of Wisconsin, Madison, WI, United States; ²Department of Radiology, University of Wisconsin, Madison, WI, United States

This study aims to determine the effects of residual contrast agent on radially encoded flow sensitive MR scan quality for cardiac and renal MRI.  Examination of vessel signal and diagnostic quality of the vasculature suggests significant improvement in vessel visualization following contrast administration in most vessels.  This improvement in vessel conspicuity was not seen in the renal arteries, where segmental vessel visualization was reduced, which we hypothesize is due to decreased contrast from accumulation of the agent in the renal parenchyma.

                  1391.     Spontaneous Cervical Artery Dissection: An Inflammatory Disease? Results of a Prospective Observational PET-CT and MRI Study

Tobias Saam¹, Thomas Pfefferkorn², Maximilian Habs¹, Marcus Hacker³, Axel Rominger³, Clemens C. Cyran¹, Martin Dichgans², Maximilian F. Reiser¹, Konstantin Nikolaou¹

¹Clinical Radiology, University of Munich, Munich, Bavaria, Germany; ²Neurology, University of Munich, Munich, Bavaria, Germany; ³Nuclear Medicine, University of Munich, Munich, Bavaria, Germany

Spontaneous cervical artery dissection (sCAD) is a frequent cause of ischemic stroke in young adults. The pathogenesis of sCAD is poorly understood. The aim of this study was to use PET/CT and MRI to estimate the prevalence of perivascular inflammation in sCAD. This study demonstrates that inflammatory changes at the site of the arterial dissection are common in sCAD patients. In a subset of these patients, perivascular inflammation was not confined to the site of the dissection, suggesting that vessel wall inflammation might play a role in the pathogenesis of sCAD.

                  1392.     Nonenhanced Spin-Labeling MR Angiography of Hepatic Arteries: Comparison of 3.0-T and 1.5-T Imaging

Masaaki Akahane¹, Jiro Sato¹, Izuru Matsuda¹, Shuhei Komatsu¹, Yasushi Watanabe², Yoshiro Satake², Naoyuki Takei³, Kuni Ohtomo¹

¹Radiology, University of Tokyo, Bunkyo-ku, Tokyo, Japan; ²Clinical Radiology, University of Tokyo, Bunkyo-ku, Tokyo, Japan; ³Japan Applied Science Laboratory, GE Healthcare Japan, Hino-shi, Tokyo, Japan

Nonenhanced spin-labeling MRA at 3.0 T is promising because of improved signal-to-noise ratio, but the influence of changes in relaxation times and field inhomogeneity on the image quality should be assessed. Eighteen volunteers underwent nonenhanced spin-labeling MRA using respiratory-gated balanced steady state free precession sequence with both Signa HDx 1.5-T and Signa HDx 3.0-T scanners (GE Healthcare, Milwaukee, WI). Contrast between PHA and the liver parenchyma was significantly higher at 3.0 T than 1.5 T. Fat suppression was more homogeneous at 1.5 T. Major anatomical variations were able to be evaluated sufficiently on both 3.0-T and 1.5-T images.

                  1393.     Effect of Flip Angle on Volume Flow Measurement with Non-Triggered Phase-Contrast MR

Hisashi Tanaka¹, Norihiko Fujita, Kenya Murase

¹Radiology, Osaka University, Suita, Osaka, Japan

Volume flow rates of the bilateral internal carotid artery and the basilar artery were measured with cine and non-triggered phase-contrast MR imaging. For non-triggered phase-contrast imaging, flip angles of 4, 15, 60 and 90�‹ were used for 40 volunteers and of 8, 15 and 30�‹ for 54 volunteers. The ratio of volume flow rate obtained with non-triggered phase-contrast imaging to that obtained with cine phase-contrast imaging significantly increases with an increase in the flip angle. The mean ratios lie within a relatively narrow range of +/- 15 % with a wide range of flip angles of 8 to 90�‹.

                  1394.     125 µm³ Spatial Resolution Steady State MRA of the Upper Legs with a Blood Pool Contrast Agent Using the Quadrature Body Coil at 1.5T

Dariusch Reza Hadizadeh¹, Guido Matthias Kukuk¹, Marius Kaschner¹, Carsten Meyer¹, Kai Wilhelm¹, Arne Koscielny², Frauke Verrel², Jürgen Gieseke¹, Hans Heinz Schild¹, Winfried Albert Willinek¹

¹Radiology, University of Bonn, Bonn, NRW, Germany; ²Vascular surgery, University of Bonn, Bonn, NRW, Germany

The blood pool contrast agent (BPCA) gadofosveset trisodium provides high vessel-to-background contrast during a prolonged imaging time window. 125 µm³ high spatial resolution 3DMRA (HRMRA) at 1.5T was acquired with the quadrature body coil only after application of the BPCA in 7 patients who suffered from peripheral arterial occlusive disease. Stenosis grading was compared to DSA. Overall image quality was rated diagnostic in all patients and stenosis grading in HRMRA matched with that in DSA in all patients. HRMRA provided high SNR and CNR in arterial and venous vessels. 125 µm³ HRMRA is feasible using a quadrature body coil only.

                  1395.     Hybrid Calf Magnetic Resonance Angiography Using a Time Resolved Technique

Jeremy Douglas Collins¹, Philip Hodnett¹, Timothy Scanlon¹, Sven Zuehlsdorff², James Carr¹

¹Radiology, Northwestern University, Chicago, IL, United States; ²Siemens Healthcare, MR Research and Development

Evaluation of a hybrid magnetic resonance angiography in a patient cohort using a low-dose time-resolved sequence along with a conventional bolus-chase technique. Despite a lower spatial resolution, the time-resolved sequence achieved a high accuracy for stenosis compared to the reference standard bolus-chase examination, with clear separation of the arterial and venous phases of vascular filling in 95% of patients and identification of retrograde filling. This hybrid technique enables assessment of potential target vessels with an average supplemental gadolinium dose of 0.04 mmol/kg and has become the clinical standard at our institution.

                  1396.     Fresh Blood Imaging Versus Contrast Enhanced MRA with DSA as the Reference Standard

Rakesh K. Puni¹, M J. Henderson¹, Lowri Morus¹, C Green¹, Faiza Admiraa-Behloul², S Roy-Choudhury¹

¹Heart of England NHS Foundation Trust, Birmingham, United Kingdom; ²MR-BU, Toshiba Meidcal Systems Europe, Zoetermeer, Netherlands

With Nephrogenic systemic fibrosis (NSF) receiving considerable attention, non-contrast enhanced (NCE) MRA appears to be a feasible alternative to contrast enhanced (CE) MRA. Fresh Blood Imaging (FBI) is a NCE technique that was introduced in late 90s by M Miyazaki and co-workers, and has gained popularity only very recently  after the NSF-Gadolinium link has been reported in patients with impaired renal function. The purpose of this pilot study was to compare FBI technique to CE-MRA using DSA as the reference  standard.

                  1397.     Non-Contrast-Enhanced Whole-Body MR Angiography

Katsumi Nakamura¹, Akiyoshi Yamamoto¹, Riichiro Nagashima¹, Kentaro Haraoka¹, Mitsue Miyazaki²

¹Radiology, Tobata Kyoritsu Hospital, Kitakyushu, Fukuoka, Japan; ²Toshiba Medical Research Institute, USA, Vernon Hills, IL, United States

Non-enhanced whole-body MRA combined with several optimized non-enhanced MRA methods appears to be an optimal and non invasive approach to systemic arterial imaging.

                  1398.     Navigator-Gated Quiescent Interval Single Shot for Pelvic MR Angiography

Christopher Glielmi¹, Xiaoming Bi¹, Ioannis Koktzoglou², Philip Hodnett³, Sven Zuehlsdorff¹, Robert R. Edelman²

¹Cardivascular MR R&D, Siemens Healthcare, Chicago, IL, United States; ²Radiology, NorthShore University HealthSystem, Evanston, IL, United States; ³Radiology, Northwestern University, Chicago, IL, United States

Quiescent Interval Single Shot (QISS) is a promising new method for non-contrast magnetic resonance angiography (MRA) with high diagnostic potential.  However, respiratory motion can cause stair-step artifacts in some regions including the iliac arteries.  In this study, we present navigator-gated QISS which gates the data acquisition based on diaphragm position to minimize respiratory artifacts.  Our approach provides image quality consistently comparable to breath-holding with absence of respiratory artifacts seen in standard free breathing approaches.  We recommend navigator-gated QISS as a free breathing alternative to breath-holding, further improving the diagnostic quality of QISS.

                  1399.     Value of Three-Dimensional Contrasted-Enhanced MR Angiography in Diagnosis and Treatment of Aortic Dissection

Qi Liu¹, Ping jian Lu¹, Fei Wang¹, li Wang¹

¹Radiology, Changhai Hospital, Second Military Medical University, Shanghai, China

3D CE-MRA can determine the type of dissection; display the true and false lumina, intimal flap, location and size of the initial entry and its relationship with the neighboring arterial orifice, and presence and amount of thrombus in false lumen. These data are important for the planning of surgical and endovascular therapy. Furthermore, it does not require iodinated contrast material, is radiation free, and has low morbidity. It combines the advantages of arterial angiography with those of MR imaging and, unlike CT angiography, does not require the removal of bone structures for adequate visualization of the vasculature.

                  1400.     Measuring Pulmonary Transit Time by 2D Magnetic Resonance Dynamic Imaging in Heart Failure Patients

Jie Jane Cao^1,2, Yi Wang, Jeannette McLaughlin, Michael Passick, Nathaniel Reichek

¹St Francis Hospital, Roslyn, NY, United States; ²State University of New York at Stony Brook, Stony Brook, NY, United States

We developed a 2D dynamic acquisition to measure pulmonary transit time in normals and heart failure patients and investigated the impact of temporal resolution on pulmonary transit time measurement.

                  1401.     Non-Contrast MR Angiography of the Toes: Correlations with Age and Gender

Jun Isogai¹, Mitsue Miyazaki², Hideo Hatakeyama¹, Takeshi Shimada¹, Takashi Yamada¹, Tomoko Miyata³, Kenji Yodo³, Ken Kudou³

¹Radiology, Hasuda Hospital, Hasuda, Saitama, Japan; ²Toshiba Medical Research Institute USA, United States; ³Toshiba Medical Systems Corp., Japan

Visualization of toe arteries is quite difficult using conventional nonenhanced MR angiography, such as time-of-flight due to the tortuous arterial trees and slow-velocity, especially in older female toes. Gadolinium-enhanced MRA also has several problems with injection rates, the amount of contrast material, and the separation of arteries from veins. Due to the recent concerns of Gadolinium-related Nephrogenic Systemic Fibrosis (NSF), nonenhanced MRA solutions have gained interest. Depiction of small arteries of the toes was investigated using time-spatial labeling inversion pulse (time-SLIP) in combination with a swap phase encode extended data (SPEED) acquisition.

                  1402.     Fat Saturation Techniques in Non-Contrast Enhanced B-SSFP MRA of the Renal Arteries.

Anne Dorte Blankholm¹, Won Yong Kim^2,3, Brian Stausbøl-Grøn¹, Michael Pedersen⁴, Steffen Ringgaard⁴

¹MR-Centre, Dept. of Diagnostic Imaging, Århus University Hospital, Skejby, Århus N, Denmark; ²MR-Centre, , Århus University Hospital, Skejby, Århus N, Denmark; ³Department of Cardiology, Århus University Hospital, Skejby, Århus N, Denmark; ⁴MR-Centre, Århus University Hospital, Skejby, Århus N, Denmark

Due to the risk for inducing nephrogenic systemic fibrosis (NSF) there is a need for developing angiography without the use of contrast agents, in particular for patients with renal disease.  MRA of the renal arteries was obtained using a balanced steady-state-free-precession (B-SSFP) method with a slab selective inversion prepulse in combination with ProSet, SPAIR and SPIR fat saturation and the images were compared with respect to fat suppression and CNR.  The ProSet technique (water selective excitation with binomial pulses) were most effective for fat saturation and produced highest vessel/muscle CNR using this sequence.

                  1403.     Non-Contrast MR Angiography of the Subclavian Arterial Branch Using 3D Half-Fourier FSE with Time-SLIP

Jun Isogai¹, Mitsue Miyazaki², Takeshi Shimada¹, Hideo Hatakeyama¹, Takashi Yamada¹, Tomoko Miyata³, Kenji Yodo³, Ken Kudou³

¹Radiology, Hasuda Hospital, Hasuda, Saitama, Japan; ²Toshiba Medical Research Institute USA, United States; ³Toshiba Medical Systems Corp., Japan

Visualization of the subclavian arterial branches is quite difficult using conventional nonenhanced time-of-flight MR angiography due to the tortuous arterial trees and small vessels. Gadolinium-enhanced MRA also has several problems with injection rates, the amount of contrast material, and venous superimposition. Due to the recent concerns of Gadolinium-related Nephrogenic Systemic Fibrosis (NSF), nonenhanced MRA solutions have gained interest. Visualization of small arteries of the subclavian arterial branches was investigated using 3D half-Fourier FSE images combined with time-spatial labeling inversion pulse (time-SLIP).

                  1404.     Non-Contrast Enhanced MRA in the Preoperative Planning of Abdominal Perforator Surgery for Postmastectomy Breast Reconstruction

J A. Clavero¹, Mitsue Miyazaki², Faiza Admiraa-Behloul³, X Alomar¹, J Masia⁴, G Pons⁴

¹Diagnostic Imaging, Clinica Creu Blanca, Barcelona, Spain; ²Toshiba Medical Research Institute, Vernon Hills, United States; ³Toshiba Medical Systems Europe, Zoetermeer, Netherlands; ⁴Plastic Surgery, Free University of Barcelona, Barcelona, Spain

Post-mastectomy autologous breast  reconstruction using abdominal perforator flaps gained popularity because it offers a natural soft breast mound, and preserves the donor site muscle and function. Because the vascular anatomy of the abdominal wall is highly variable between individuals, a detailed accurate preoperative vascular map of the abdomen can significantly reduce the operating time, with a better surgical outcome. MDCTA proved to be very useful for this purpose [1], however it requires ionizing contrast agents and radiation. the purpose of this work was to investigate the role of non-contrast enhanced MR angiography (NC-MRA), as compared to MDCTA, in the preoperative evaluation of the vascular anatomy of the abdominal wall for abdominal perforator flap surgery in post-mastectomy breast reconstruction.

                  1405.     Intraindividual Comparison of Static, High Resolution and Dynamic 4D Contrast Enhanced Magnetic Resonance Angiography of the Lower Legs

Johannes T. Heverhagen¹, Sabrina El Tobgui, Mykhylo Burbelko, Klaus J. Klose

¹Department of Diagnostic Radiology, Philipps University, Marburg, Germany

The purpose of this study was to intraindividually compare static, high resolution and dynamic CE MRA of the lower legs in patients with severe peripheral arterial occlusive disease (PAOD). State of the art 4D MRA of the lower legs for suspected PAOD provides excellent image quality without venous overlay, an artefact that severely influences diagnostic quality in static MRAs. It is user independent proven by a Cohen´s kappa of 0.92. 4D MRA of the lower legs should be employed in all patients undergoing CE MRA for suspected PAOD.

                  1406.     Preliminary Experience in Evaluation of Disease Severity and Activity of Takayasu Arteritis with Whole-Body MRA and Vessel Wall Imaging

Jiang Lin¹, Dan li², Fu-hua Yan², Jiang-hua Wang²

¹Radiology, Shanghai zhongshan hospital, Shanghai, China; ²shanghai zhongshan hospital

Takayasu Arteritis is a systemic disorder which mainly involves medium- and large-sized arteries. As it progresses, many kinds of luminal pathology may appear, such as stenosis, occlusion and aneurysm. However, at an early stage, the vessel lumen often remains unchanged while inflammation or thickening of the vessel wall may already exist. Furthermore when the disease is active, the mural tissue may be avidly enhanced. Early diagnosis and comprehensive assessment of its severity and activity are required which may influence treatment procedure and outcome. In this study we explored the potential of Whole-body MRA for comprehensive diagnosis of Takayasu Arteritis with postcontast vessel wall imaging.

                  1407.     Steady State Imaging with Blood Pool Contrast Agent MRA in Patients with Critical Lower Limb Ischaemia for Venous Mapping Bypass Graft Assessment - Initial Experience

Giles Roditi¹, Douglas Orr²

¹Radiology, Glasgow Royal Infirmary, Glasgow, Scotland, United Kingdom; ²Vascular Surgery, Glasgow Royal Infirmary, Glasgow, Scotland, United Kingdom

Patients for bypass grafting need vein suitability assessed.  High resolution blood pool contrast agent imaging compared to ultrasound in 20 patients with gadofosveset for MRA.  Deep veins assessed for patency, quality & calibre.    Vein diameters assessed as similar calibre. MRA showed more veins, divisions and perforating tributaries.  MRI studies judged more informative than the descriptive ultrasound reports except for one patient with poor image quality due to severe pain during scan. Lower limb MRA performed with blood pool contrast agent and steady state imaging may obviate additional ultrasound examination in assessment for potential bypass grafting. Challenge to ensure consistent image quality.

                  1408.     Combined Renal and Peripheral MRA with a New Technique at 3.0 T

Philip Anthony Hodnett¹, Ioannis Koktzoglou², John Sheehan^2,3, Amir Davarpanah³, Christopher Glielmi⁴, Robert Edelman²

¹Radiology, Northwestern Memorial Hospital, Chicago, IL, United States; ²Northshore University Healthcare System; ³Northwestern University; ⁴Siemens Healthcare, MR Research and Develpoment, Chicago, IL

Introduction: The proliferation and increased use of 3.0 T MR Systems offers both potential advantages and difficulties in the implementation of unenhanced MRA techniques. Materials and Methods: To perform an initial feasibility study followed by technical optimization of quiescent interval single shot (QISS) magnetic resonance angiography for renal artery and lower extremity evaluation. The study was performed with IRB approval. Seven healthy volunteers underwent combined unenhanced Renal and Peripheral Lower Limb Angiography  Conclusion: We report the feasibility of the QISS technique as a potential MRA technique for combined dual Renal and Lower extremity unenhanced MRA at 3.0 T

MRA Preclinical Technical Development

                  1409.     Black-Blood Restricted Field of View Sequence for Pre-Ablation Imaging of the Atria

Christian Stehning¹, Dennis Caulfield², Benjamin R. Knowles², Steffen Weiss¹, Tobias Schaeffter²

¹Philips Research Europe, Hamburg, Germany; ²Division of Imaging Sciences, King's College, London, United Kingdom

Knowledge of the atrial wall anatomy is important for the subsequent RF ablation procedure. A restricted FOV MR sequence which allows exclusive imaging of the atria was evaluated in the present study. It provides a clear depiction of the atrial wall thickness with submillimeter resolution in a clinically acceptable scan time and mitigates motion artifacts, particularly in patients with cardiac arrhythmia.

                  1410.     3D Non-Contrast-Enhanced MRA Using Flow-Sensitive Dephasing (FSD) Prepared Balanced SSFP: Identification of the Optimal First-Order Gradient Moment

Zhaoyang Fan^1,2, Xiaoming Bi³, Xiangzhi Zhou¹, Sven Zuehlsdorff³, Rohan Dharmakumar¹, James Carr¹, Debiao Li^1,2

¹Radiology, Northwestern University, Chicago, IL, United States; ²Biomedical Engineering, Northwestern University, Evanston, IL, United States; ³Cardiac MR R&D, Siemens Healthcare, Chicago, IL, United States

A noncontrast MRA technique using ECG-triggered 3D balanced SSFP with flow-sensitive dephasing (FSD) preparation has recently been validated in the distal lower extremities of healthy volunteers. The FSD’s first-order gradient moment, m1, is shown to be the most important parameter to determine angiographic quality. This work developed a 2D m1-scout approach in which incremental m1 values were rapidly used to acquire 2D black-blood images and the optimal m1 value can be selected for 3D MRA. Its usefulness is validated on flow phantom and five healthy volunteer legs. This approach may also improve FSD-based vessel wall imaging.

                  1411.     Accelerating Time-Resolved MRA with Multi-Echo Acquisition

Hyun Jong Jeong¹, Christopher S. Eddleman², Saurabh Shah³, Nicole Seiberlich⁴, Mark A. Griswold⁴, James C. Carr⁵, Timothy J. Carroll^1,5

¹Biomedical Engineering, Northwestern University, Chicago, IL, United States; ²Neurosurgery, Northwestern University, Chicago, IL, United States; ³Siemens Medical Solutions, Chicago, IL, United States; ⁴Radiology, University Hospitals of Cleveland, Cleveland, OH, United States; ⁵Radiology, Northwestern University, Chicago, IL, United States

A new 4D MRA technique called Contrast-enhanced Angiography with Multi-Echo and RAdial k-space (CAMERA) is introduced.   With CAMERA, temporal footprint is reduced by a factor of 2 without parallel imaging or undersampling, while increasing SNR.  Higher frame rates are achieved by radial sliding window reconstruction.  Further acceleration is also possible by incorporating parallel imaging.  The technique has been applied to MRA in the intracranial, pulmonary, and renal vessels.

                  1412.     Non-Contrast Enhanced Pulmonary Vein MRA with a Spatially Selective Inversion Preparation Sequence

Peng Hu¹, Michael L. Chuang, Thomas H. Hauser, Kraig V. Kissinger, Beth Goddu, Lois A. Goepfert, Neil M. Rofsky², Warren J. Manning, Reza Nezafat

¹Beth Israel Deaconess Medical Center, Bosto, MA, United States; ²Radiology, Beth Israel Deaconess Medical Center

We propose a non-contrast-enhanced free-breathing ECG-gated gradient-echo sequence with a sagittal slab-selective inversion for pulmonary vein (PV) MRA. The inversion pulse was applied to suppress structures adjacent to the left atrium (LA) and PVs, thereby, improving the conspicuity of the PV/LA. The inversion slab thickness and inversion time were optimized on volunteers to be 60mm and 500ms, respectively.  The proposed technique significantly increased the CNR between the LA/PV and adjacent structures by 4-20 fold with minimal loss of signal in LA/PV. The PV size measurements of the proposed technique correlated well with clinical contrast-enhanced MRA on 9 atrial fibrillation patients.

                  1413.     Unenhanced Techniques for Peripheral MRA: Phantom Evaluation in the Setting of Triphasic Flow and Stenosis

Erik John Offerman¹, Philip Anthony Hodnett, ¹², Robert R. Edelman¹, Ioannis Koktzoglou¹

¹Department of Radiology, Northshore University Healthsystem, Evanston, IL, United States; ²Department of Radiology, Northwestern Memorial Hospital, Chicago, IL, United States

The link between NSF and Gadolinium has renewed interest in unenhanced MRA techniques that can match the diagnostic potential of contrast-enhanced MRA.  Predominant peripheral MRA techniques are evaluated in a 50% stenotic triphasic flow phantom.  The techniques are compared by measuring the signal within the stenosis and observing coronal thin MIPs at select flow velocities.  The performance of the techniques is dependent on the peak systolic flow velocity of the waveform.  Each technique exhibited signal dropout in the area of stenosis at different velocities, and some experienced dropout proximal and distal to the stenosis.  Signal vs. flow velocity trend differed between 50% and no stenosis conditions.

                  1414.     High-Resolution Ex Vivo Magnetic Resonance Angiography: A Feasibility Study on Biological and Medical Tissues

Anne S. Rasmussen¹, Henrik Lauridsen², Bjarke G. Jensen², Steen Fjord Pedersen¹, Tobias Wang², Niels Uldbjerg³, Michael Pedersen¹

¹MR-research Centre Aarhus University Hospital, Aarhus, Denmark; ²Department of Biology, Aarhus University, Aarhus, Denmark; ³Department of Gynaecology and Obstetrics, Aarhus University Hospital, Aarhus, Denmark

In vivo angiography is often used in biomedical science. Ex vivo angiography of excised organs or whole body is however rarely used due to the lack of appropriate contrast solutions capable of entering and staying in the vasculature after amputation or death. This study aims to develop contrast solutions and methods for ex vivo MRA and CTA. Two solutions were produced and used for MRA and CTA in four different species. MRA was found to have an advantage to CTA in situations where blood vessels were in close proximity to bones that can interfere with the signal in CTA.

                  1415.     Flow Sensitivity Analysis of Variable Refocusing Angle 3D FSE

Wayne R. Dannels¹, Xiangxian Shou², Robert Anderson¹, Mitsue Miyazaki³

¹Toshiba Medical Research Institute, Mayfield Village, OH, United States; ²Department of Physics, Case Western Reserve University, Cleveland, OH; ³Toshiba Medical Research Institute, Chicago, IL, United States

FSE sequences can be adapted either to maintain brightness or to suppress the signal of moving blood. Subtraction methods with FSE can generate angiographic images without injection of contrast agents. 3D FSE variants with variable refocusing angle (VRA) of the echo train are naturally suitable for high scanning efficiency and SAR reduction. Flow sensitivity dependienceis on sequence parameters are analyzed for 3D VRA FSE angiography applications. In vivo testing shows that flow sensitivity can be maintained while SAR is reduced.

                  1416.     Contrast Enhancement for SSFP Angiography with Signal Compensation and Compressed Sensing

Tolga Çukur¹, Michael Lustig¹, Dwight Nishimura¹

¹Department of Electrical Engineering, Stanford University, Stanford, CA, United States

Magnetization-prepared SSFP angiography can produce vessel images without contrast agents, when coupled with segmented k-space acquisitions. However, the preparation needs to be frequently repeated to effectively capture the transient contrast. Because the vessels have more dominant high-spatial-frequency content compared with the background, compensating for the transient signal decay significantly improves the contrast and resolution, while the resulting noise in sparse angiograms is reduced with compressed sensing.

                  1417.     Breathhold Inhance Inflow IR (BH-IFIR) with a Novel 3D Recessed Fan Beam View Ordering

Naoyuki Takei¹, Manojkumar Saranathan², Mitsuharu Miyoshi¹, Tetsuji Tsukamoto¹

¹Applied Science Laboratory, GE Healthcare, Hino, Tokyo, Japan; ²Applied Science Laboratory, GE Healthcare, Rochester, MN, United States

Respiratory-gated inflow related non-contrast MR Angiography with selective inversion pulse (inflow IR) has been used clinically in abdomen region. However the use of respiratory gating suffers from motion artifact caused by unstable breathing during scan in a patient. A novel 3D multi-segmented view ordering was proposed to resolve it with breathhold scan. The efficient view ordering allows long data acquisition window while keeping image contrast, resulting in scan time reduction due to decreased number of segments. The our initial study has investigated the possibility of breathhold scan and demonstrated that high contrast between artery and background tissues and uniform blood signal along with reduced scan time were achieved.

                  1418.     Vastly Undersampled Isotropic Projection Reconstruction and HYPR for Time Resolved CE-MRA of the Peripheral Vessels

Lauren Keith¹, Steve Kecskemeti¹, Yijing Wu¹, James Holmes², Kang Wang¹, Reed Busse², Frank Korosec^1,3

¹Medical Physics, University of Wisconsin-Madison, Madison, WI, United States; ²Applied Science Lab, GE Healthcare, Madison, WI, United States; ³Radiology, University of Wisconsin-Madison, Madison, WI, United States

Vastly undersampled Isotropic Projection Reconstruction (VIPR) [1] techniques have been successfully utilized for time-resolved contrast-enhanced MR angiography (CE-MRA) studies. In this work, we explore the benefits of using the VIPR k-space sampling trajectory, in combination with the HYPR LR processing method, for obtaining high spatial and temporal resolution CE-MRA images of the lower extremities.

                  1419.     High Resolution MR Flouroscopy

Parmede Vakil¹, Hyun J. Jeong, Himanshu Bhat, Christopher Eddleman², Tiomthy J. Carroll

¹Radiology, Northwestern University, Chicago, IL, United States; ²Northwestern Memorial Hospital

We present a novel 2D MRI pulse sequence for CE MRA with sliding window reconstruction and complex subtraction. Our pulse sequence produces a time-series of projection images through a thick volume. Time-series images have high spatial resolution (0.57 mm x 0.57 mm) capable of visualizing small arteries, small temporal foot print (~2 seconds/acquisition) and high frame rate (6 fps) making them useful for imaging hemodynamics of intracranial vascular pathologies such as AVMs or aneurysms. We are currently engaged in an ongoing study applying our sequence to AVM patients. Imaging results will be presented.

                  1420.     Rapid Non-Contrast-Enhanced Renal Angiography Using Multiple Inversion Recovery

Hattie Zhi Chen Dong¹, Pauline W. Worters², Holden H. Wu^1,3, Tolga Çukur¹, Brian Andrew Hargreaves², Dwight G. Nishimura¹, Shreyas S. Vasanawala²

¹Electrical Engineering, Stanford University, Stanford, CA, United States; ²Radiology, Stanford University, Stanford, CA, United States; ³Cardiovascular Medicine, Stanford University, Stanford, CA, United States

We investigate the use of multiple inversion recovery (MIR) preparation for rapid non-contrast-enhanced renal angiography without image subtraction or breath-holding. MIR preparation consists of selective spatial saturation followed by several nonselective inversions to suppress a range of background T₁ species, while maintaining signal from arterial inflow. Two readout approaches were chosen: alternating TR balanced SSFP (ATR-bSSFP) to provide good blood SNR with added fat suppression, and half-Fourier single-shot FSE (SSFSE) to fully capture the MIR contrast preparation. Using the two sequences, projective renal angiograms were produced in 3 and 1 heartbeat(s) respectively.

                  1421.     Non-Enhanced Vs. Contrast-Enhanced MRA at 7Tesla:  a Feasibility and Comparison Trial.

Lale Umutlu¹, Thomas C. Lauenstein¹, Oliver Kraff², Stefan Maderwald², Stephan Orzada², Sonja Kinner¹, Christina Heilmaier¹, Gerald Antoch¹, Mark E. Ladd², Harald H. Quick^2,3

¹Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany; ²Erwin L.Hahn Institute for Magnetic Resonance Imaging; ³Institute for Medical Physics, Friedrich-Alexander-University Erlangen-Nürnberg

Aim of this pilot study of 7T MRA was to investigate the diagnostic capability of non-enhanced 7T MRA and the feasibility of contrast-enhanced ultrahighfield MRA. 8 healthy subjects were examined on a 7T whole-body MR system utilizing a custom-built 8-channel RF transmit/receive body coil. Qualitative and quantitative analysis results demonstrate the diagnostic superiority of TOF-MRA among the non-enhanced sequences as well as its diagnostic capability towards contrast-enhanced MRA. In Conclusion, this first pilot study of dedicated 7TMRA shows the feasibility of contrast-enhanced MRA, as well as the diagnostic ability of TOF MRA e.g. in case of renal insufficiency.

                  1422.     Peripheral Arterial Imaging with a Continuously Moving Table Time-Of-Flight View-Sharing Technique

Sandra Huff¹, Michael Markl¹, Ute Ludwig¹

¹Department of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany

To improve the limited coverage of Time-of-Flight (TOF) arteriography, this study addresses the combination of 2D axial TOF and Continuously Moving Table (CMT) acquisitions for imaging the peripheral arteries. Since arterial blood flow is very pulsatile in the periphery, inflow in acquired slices and thus blood signal intensity depends on the time point of acquisition within the cardiac cycle. To compensate for this artefact, a new CMT gradient echo sequence has been designed, that provides several arterial images per slice position respectively per cardiac cycle and is based on a view sharing principle. Background signal was suppressed via image subtraction.

                  1423.     Visualization of Tumor Angiogenesis in Lung Cancer Overexpressing Different VEGF Isoform in a Murine  Xenograft Model by Using High Resolution 3Dimentional Contrast-Enhanced Microscopic MR Angiography

Chia-Ming Shih^1,2, Ang Yuan³, Chih-Yuan Chen², Cheng-Hung Chou², Hao-Wei Cheng³, Pan-Chyr Yang³, Jyh- Horng Chen¹, Chen Chang²

¹Institute of Biomedical Electronics and Bioinformatics, National Taiwan University, Taipei, Taiwan; ²Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan; ³National Taiwan University Hospital, Taipei, Taiwan

Evaluation of the different effects of VEGF isoforms such as VEGF121, VEGF165 and VEGF189 on tumor feeding vessels and intratumor vessels may offer important new insight into the process of tumor angiogenesis in non-small cell lung cancer. This study was aimed to visualize tumor angiogenesis induced by different VEGF isoform in non-small cell lung cancer in a murine xenograft model by using High Resolution 3Dimentional Contrast Enhanced- Microscopic MR Angiography (HR 3D CE-mMRA).

                  1424.     Non-Contrast-Enhanced Renal Venography Using Spatial Labeling with Multiple Inversion Pulses ( SLEEK )

Hao Shen¹, Guang Cao²

¹Applied Science Laboratory, GE Healthcare, Beijing, China; ²Applied Science Laboratory, GE Healthcare, Hong Kong, China

Renal venogram is important in clinical diagnosis but difficult to image with the existing MRI technique. In this study, we developed a non-contrast-enhanced renal venography using a spatial labeling with multiple inversion pulses prepared balanced steady-state free precession sequence.

                  1425.     Fast Vessel Scout Imaging Based on Continuously Moving Table Acquisitions of Projection Data

Sandra Huff¹, Michael Markl¹, Ute Ludwig¹

¹Department of Diagnostic Radiology, Medical Physics, University Hospital Freiburg, Freiburg, Germany

MRA of the peripheral arteries is typically based on a contrast enhanced multistation bolus-chase approach, which requires good synchronization of data acquisition, table motion and arterial passage of the contrast agent bolus. These challenges imply the need for careful planning for the consecutive acquisitions of the several stations and prior knowledge of the vessel geometry would thus be desirable. This study presents the implementation of a fast peripheral vessel scout based on Continuously Moving Table acquisition of projection data with Time-of-Flight (TOF) contrast. The variation of arterial TOF signal during the cardiac cycle was exploited to enhance blood-background contrast.

                  1426.     Optimization and Comparison of Non-Contrast-Enhanced Inflow-Sensitive Inversion Recovery BSSFP for  Renal and Mesenteric MRA at 1.5T and 3.0T

Caroline Denison Jordan^1,2, Pauline Wong Worters¹, Shreyas S. Vasanawala¹, Bruce L. Daniel¹, Marc T. Alley¹, Moritz F. Kircher¹, Robert J. Herfkens¹, Brian A. Hargreaves¹

¹Radiology, Stanford University, Stanford, CA, United States; ²Bioengineering, Stanford University, Stanford, CA, United States

Contrast-enhanced MR angiography is a widely accepted technique for imaging the kidneys, but there are many reasons to explore non-contrast-enhanced MRA methods, including contraindication of gadolinium for patients with kidney disease.  We evaluated one non-contrast enhanced MRI technique which has shown promising results: respiratory-triggered bSSFP with In Flow Inversion Recovery (IFIR). We optimized the inversion times at 1.5T and 3T, and then quantitatively and qualitatively compared images of renal and mesenteric arteries. We found better relative contrast and better visualization of renal and mesenteric arteries at 3T.  An inversion time of 800 ms gave the optimal relative contrast.

                  1427.     Feasibility of Refocused Turbo Spin Echo (RTSE) for Clinical Noncontrast MRA

Samuel W. Fielden¹, John P. Mugler III^1,2, Patrick T. Norton^2,3, Klaus D. Hagspiel^2,3, Christopher M. Kramer^2,3, Craig H. Meyer^1,2

¹Biomedical Engineering, University of Virginia, Charlottesville, VA, United States; ²Radiology, University of Virginia, Charlottesville, VA, United States; ³Medicine, University of Virginia, Charlottesville, VA, United States

rTSE hybridizes the increased signal provided by the 180° refocusing RF pulses of RARE and the better flow performance of the fully-refocused gradients and phase alternation of balanced SSFP.   Here we demonstrate the feasibility of the rTSE sequence in a clinical setting by acquiring angiograms via the rTSE sequence in patients scheduled for peripheral runoff examinations and, in one patient, by comparing the rTSE angiogram to a TOF angiogram.

                  1428.     Whole Body TOF Mouse Magnetic Resonance Angiography

William Lefrançois¹, Wadie Ben Hassen, Stéphane Sanchez, Jean-Michel Franconi, Eric Thiaudière, Sylvain Miraux

¹Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS-Univ. Bordeaux 2, Bordeaux, Gironde, France, Metropolitan

Vascular diseases, particularly atherosclerosis, are a major health problem in developed countries. In some cases, stenosis can become critical and cause coronary heart disease necessitating surgical interventions. Therapy planning in patients with multiple stenosis could be facilitated by using whole body angiography. MR angiography (MRA) method currently used on human, is first-pass MRA using a Gadolinium contrast agent. However, this method can not be used on small animal models. This study aimed to develop a fast Time-of-Flight-MRA method able to screen the whole body in reasonable acquisition times and assess the degree and extent of stenosis.

                  1429.     The Origins of Bright Blood MPRAGE at 7 Tesla and a Simultaneous Method for T1 Imaging and Non-Contrast MRA

John W. Grinstead¹, William Rooney², Gerhard Laub

¹Siemens Healthcare, Portland, OR, United States; ²Oregon Health and Science University

MPRAGE is a widely used pulse sequence for T1-weighted anatomical imaging. It has been reported that blood appears extremely bright in MPRAGE at 7 Tesla, and provides excellent vascular information. However, the mechanism for this has not been completely explained. The present work explains the primary source of bright blood MPRAGE at 7 Tesla, and based on this understanding proposes a new technique providing simultaneous high-resolution T1 MPRAGE imaging and non-contrast angiography with excellent background suppression.

                  1430.     Volumetric Phase Contrast Flow Imaging with Multiple Station Isocenter Acquistion Substantially Improves Flow Results

Andreas Greiser¹, Mehmet Akif Gulsun², Arne Littmann¹, Jens Guehring², Edgar Mueller¹

¹Siemens AG Healthcare Sector, Erlangen, Germany; ²Siemens Corporate Research, Princeton, NJ, United States

Vector-encoded MR phase contrast acquisitions covering a bigger volume show larger errors in velocity due to eddy currents and gradient non-linearities. A new scan method is presented that acquires the volumetric dataset in multiple z-isocentered steps. The resulting corrected velocity images and the influence on the flow quantification results of the descending aorta and flow field visualization were analyzed. The multiply isocentered approach results in an overall increase of peak velocity estimates and flow values. The pixelwise standard deviation of the calculated  background phase correction matrices across slices for fixed table position was 1.76 cm/sec vs. 0.61 cm/sec for z-isocentered.

                  1431.     The Essence of Half-FOV Shift Ghost Imaging

Leping Zha¹, Mitsue Miyazaki¹

¹Toshiba Medical Research Institute USA, Vernon Hills, IL, United States

Simulations with synthesized phantom image data and actual comparisons of reconstruction results from acquired imaging data show that, the ½ FOV shift ghost imaging with purposely controlled differences between the even and the odd k-space line sub-sets is essentially an alternative and practical form of complex subtraction of images from the data sub-sets, which often produces superior results compared to that from the common magnitude subtraction imaging, especially for MR angiography.

                  1432.     Accelerated Time-SLIP Cerebral MR Angiography by Use of Dual Inversion Pulse for Background Suppression

Yoshiyuki Ishimori¹, Masahiko Monma¹, Izumi Anno¹, Tomoko Miyata²

¹Department of Radiological Sciences, Ibaraki Prefectural University of Health Sciences, Ami-machi, Inashiki-gun, Ibaraki, Japan; ²Toshiba Medical Systems Co. Ltd.

Time-Spatial Labeling Inversion Pulse (time-SLIP) techniques are utilized as a non-contrast MR angiography using arterial spin labeling (ASL). However, it takes double time for subtraction process between on/off of ASL to visualize cerebral angiograms because of high signal of cerebrospinal fluid (CSF). Single acquisition time-SLIP using dual inversion pulse was investigated in the phantom and volunteer study. As a result, both of CSF and brain parenchyma were suppressed enough with appropriate inversion times. Thus cerebral angiograms could be visualized sufficiently. Accelerated time-SLIP MRA will be useful in terms of imaging time and scan plane flexibility compared to time-of-flight MRA.

                  1433.     Non Contrast MR Angio by Intrinsic Dephasing of True FISP    SMS:  Ssfp Minus Ssfp

Michael Deimling¹, Alto Stemmer¹

¹Siemens Healthcare, Erlangen, Germany

We propose an SSFP (Steady State Free Precession) sequence scheme which is based on the intrinsic very high signal sensitivity of flow phase instabilities from TR to TR interval. A straight forward modification of a true FISP sequence makes the signal susceptible to fast flow of the arteries, but leaves the flow of venes untouched; by simply subtraction of both 3D data sets, an artery only image is created. The method does not need any kind of gating or triggering to separate veins from arteries as is needed in non-contrast enhanced MRA methods like Fresh Blood Imaging.

                  1434.     Accelerated High-Resolution 3D Magnetic Resonance Angiography Using SENSE: Fast and Accurate Assessment of Carotid Artery Stenosis in ApoE Ko Mice

David Ratering¹, Christof Baltes¹, Christine Lohmann², Christian M. Matter², Markus Rudin^1,3

¹Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland; ²Institute of Physiology, University Zurich and Cardiology University Hospital Zurich, Zurich, Switzerland; ³Institute of Pharmacology & Toxicology, University Zurich, Zurich, Switzerland

High-resolution magnetic resonance angiography (MRA) enables detection and monitoring of atherosclerosis in mouse models of human disease. However, high-resolution MRA suffers from long acquisition times putting high demands on the animal’s physiological stability. Therefore the feasibility of accelerated MRA of murine supra-aortic vasculature using SENSE was investigated with regard to lesion detection and quantitative morphometric analysis. Evaluations revealed that data collection with acceleration factors R ≤ 3.3 had only minor effects on vessel delineation. No significant differences could be found for the morphometric assessment of stenotic lesions and the determination of degree of stenosis when comparing accelerated to fully-sampled data.

                  1435.     Phase-Enhancement Technique for a Hybrid-Of-Opposite-Contrast MR Angiography

Tokunori Kimura¹, Masato Ikedo²

¹MRI Systems Development Department, Toshiba Medical Systems , Otawara, Tochigi, Japan; ²MRI Systems Development Department, Toshiba Medical Systems, Otawara, Tochigi, Japan

We have proposed a MRA technique named Hybrid-of-Opposite-Contrast (HOP) MR Angiography combining time-of-flight (TOF) and flow-sensitive black-blood (FSBB) using dual-echo 3D gradient echo sequence, which was magnitude-based technique. For the purpose of further enhancing blood-to-background contrast, we proposed and assessed a new image processing technique employing corresponding phase maps for 1st echo (TOF) and 2nd echo (FSBB) so as to further enhance blood vessels white and black, respectively. Volunteer brain study was performed. Smaller vessels were further delineated by this technique than the standard magnitude-based HOP images.

                  1436.     Changes in MR Signals Associated with Organizing Processes of Venous Thrombi in Rabbits.

Yasuyoshi Kuroiwa^1,2, Atsushi Yamashita³, Tosiaki Miyati¹, Eiji Furukoji⁴, Misaki Takahashi³, Toshiya Azuma⁴, Hiroshi Sugimura⁴, Shozo Tamura⁴, Keiichi Kawai^1,5, Yujiro Asada³

¹Division of Health Sciences, Graduate School of Health Science, Kanazawa University,, Kanazawa, Ishikawa, Japan; ²Department of Pathology, ,  Faculty of Medicine, University of Miyazaki, Miyazaki, Japan; ³Department of Pathology,, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan; ⁴Department of Radiology,, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan; ⁵Biomedical Imaging Research Center, University of Fukui

To determine the potential of MR to detect venous thrombosis and to define thrombus age, we examined in vivo MR imaging of rabbit jugular vein thrombi 4 hours, 1, 2, 4 weeks after endothelial denudation and vessel ligation, and assessed the association between signal intensities and cellular and matrix contents. We demonstrated that MRI can reliably and noninvasively detect rabbit jugular vein thrombi, and that sequential changes in T2 and T1 weighted signal intensity may reflect organizing process of the venous thrombus. MRI may noninvasively detect venous thrombosis and define thrombus age which is valuable information for thrombolytic therapy.

                  1437.     Realtime Cine MRI in Mice with a Single-Shot EPI Sequence and the Karhunen–Loeve Transform

Guangping Dai¹, Yu Ding², Shuning Huang¹, Orlando P. Simonetti², David E. Sosnovik³

¹Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School; ²Dorothy M. Davis Heart and Lung Research Institute, The Ohio State University; ³Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA, United States

Realtime cine MRI of the mouse heart is reported using a single-shot EPI sequence and the Karhunen–Loeve transform. The entire mouse heart can be imaged with this technique in less than 5 minutes, using minimal sedation. This report demonstrates the ability of MRI to be used for high-throughput applications, and compete with echocardiography, in the basic science as well as and clinical settings.

                  1438.     Inflow Inversion Recovery MR Angiography of Renal Arteries at 3.0 T: A Feasibility Study

Hiromitsu Onishi¹, Tonsok Kim¹, Masatoshi Hori¹, Takahiro Tsuboyama¹, Atsushi Nakamoto¹, Hiroki Higashihara¹, Mitsuaki Tatsumi¹, Kaname Tomoda¹, Mitsuhiro Uike², Shoji Nakagami²

¹Department of Radiology, Osaka University Graduate School of Medicine, Suita, Osaka, Japan; ²MR Sales & Marketing Department, GE Healthcare Japan, Hino, Tokyo, Japan

The aim of the present study was to evaluate the feasibility of noncontrast MR angiography of the renal arteries using an Inflow Inversion Recovery (IFIR) sequence in healthy volunteers at 3.0 T. In nine of 10 cases, MR angiography with excellent image quality was obtained and both sides of renal arteries were finely delineated including peripheral branches. In four of 10 cases, two left renal arteries were observed. In addition, in one of four, two right renal arteries were also observed. The renal arteries were finely delineated by means of noncontrast MR angiography using an IFIR sequence at 3.0 T.

                  1439.     3D Isotropic Non-Contrast Approach for the Assessment of Carotid Arteries Stenosis at 3T

Ravi Teja Seethamraju¹, Michael Jerosch-Herold², Yiu-Cho Chung³, Peter Libby⁴, Marcelo F. Di Carli⁵, Raymond Y. Kwong⁶

¹MR R and D, Siemens Medical Solutions, USA Inc., Charlestown, MA, United States; ²Radiology, Brigham and Women's Hospital, Boston, MA, United States; ³MR R and D, Siemens Medical Solutions, USA Inc., Columbus, OH, United States; ⁴Cardiovascular Medicine, Brigham and Woman's Hospital, Boston, MA, United States; ⁵Nuclear Medicine, Brigham and Women's Hospital, Boston, MA, United States; ⁶Cardiovascular Imaging, Brigham and Women's Hospital, Boston, MA, United States

We present MPRAGE and SPACE as two isotropic 3D non contrast techniques for the measurement of coronary artery stenosis. While both techniques provide precise measurements of the stenosis, they complement each other with respect to characterization of plaque.

                  1440.     Non-Contrast Time-Resolved MR Angiography Combining Multiple IR and N-1 Subtraction Arterial Spin Labeling Technique

Tokunori Kimura¹, Shinichi Kitane², Kazuhiro Sueoka³

¹MRI Systems Development Department, Toshiba Medical Systems , Otawara, Tochigi, Japan; ²MRI Systems Development Department, Toshiba Medical  Enginieering, Otawara, Tochigi, Japan; ³MRI Systems Development Department, Toshiba Medical Enginieering, Otawara, Tochigi, Japan

In-flow time-resolved MR angiography technique employing non-subtraction arterial spin labeling with multiple IR (mIR) technique was proposed. It was, however, difficult for mIR to suppress background tissue of wide range of T1 values from fat to CSF. We proposed alternative N-1 subtraction technique further to suppress background tissue signals while minimizing extra acquisition time. Volunteer brain study was performed on 1.5T imager with 2 mIR pulses designed to suppress brain tissues. Resulting background signals of fat and brain parenchyma were well suppressed only by adding extra acquisition time of 16 sec for base image then subtraction.