Yosef A Berlow¹, Lisa Karstens Vingara¹, Manoj K Sammi¹, Laura E McMahon¹, Ian Tagge¹, Brendan Moloney¹, John W. Grinstead², and William D Rooney^1
1Advanced Imaging Research Center, Oregon Health & Science University, Portland, Oregon, United States, ²Siemens Healthcare, Portland, OR, United States

Brain segmentation is challenging using data collected from ultra-high magnetic field MRI instruments. Here, we present a robust approach to segment high-spatial resolution T1-w MPRAGE data sets acquired at 7T and demonstrate results from 88 healthy controls.

Christoph Moenninghoff^1,2, Oliver Kraff², Stefan Maderwald², Jan Altmeppen¹, Lale Umutlu¹, Mark E Ladd^2,3, Michael Forsting¹, and Marc Schlamann^1
1Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany, ²Erwin L. Hahn Institute for MRI, University Duisburg-Essen, Essen, Germany, ³Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Germany

Traumatic microbleeds (TMBs) are regarded as a radiological marker for diffuse axonal injury (DAI). This study compares the detection of TMBs on 3T and 7T magnetic resonance images. 8 volunteers with DAI were examined with MR scanners equipped with 32-channel head coils at both field strengths. TMBs were counted on susceptibility weighted images (SWI), with similar and 14-times increased spatial resolution at 7T. 7T SWI depicted 28% and 40% more TMBs compared to 3T with similar and higher spatial resolution, respectively. Hence, 7T SWI may optimize diagnostics of DAI in inconclusive and in medicolegal cases.

Claudiu Schirda¹, Tiejun Zhao², and Hoby Hetherington^1
1Radiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States, ²Siemens Medical Solutions, Pittsburgh, PA, United States

We demonstrate in vivo brain, fast spectroscopic imaging at 7T, using non-Cartesian rosette trajectories. Lipid suppression is achieved using an 8-channel PTX system and high field homogeneity is obtained through the use of a gradient insert system with up to 4th order shims.

Hans Hoogduin¹, Ronald Mooiweer², Giel Mens³, Joseph V Hajnal⁴, Peter Luijten², and Shaihan J Malik^4
1UMC Utrecht, Utrecht, Utrecht, Netherlands, ²UMC Utrecht, Utrecht, Netherlands, ³Philips Healthcare, Best, Netherlands, ⁴King's College London, London, United Kingdom

The effectiveness of SPIral Non Selective (SPINS) RF pulses to increase the excitation homogeneity at 7T is investigated for T1W (MP-RAGE) imaging.

Linda Marrakchi-Kacem^1,2, Alexandre Vignaud³, Johanne Germain^1,2, Julien Sein⁴, Thomas R. Henry⁵, Cyril Poupon³, Lucie Hertz-Pannier³, Stéphane Lehéricy^1,6, Olivier Colliot^1,2, Pierre-François Van de Moortele⁴, and Marie Chupin^1,2
1UPMC-Paris6, CRICM, CNRS, UMR 7225, Inserm, UMR-S975, ICM, Paris, France, ²Aramis project-team, Inria Paris-Rocquencourt, Paris, France, ³NeuroSpin, CEA, Gif-Sur-Yvette, France, ⁴CMRR, University of Minnesota, Minneapolis, MN, United States, ⁵Department of Neurology, University of Minnesota, Minneapolis, MN, United States, ⁶AP-HP, Hôpital de la Salpêtrière, CENIR, Paris, France

Imaging of the hippocampus subparts with high resolution requires long acquisition time which can generate movement artifacts inside the images. This problem can be solved using multi-slab acquisitions which reduce acquisition time but require an accurate registration method to overcome inter-slab movement. We propose an efficient registration procedure for interleaved slab acquisitions. It consists in registering the slabs containing gaps to a reference image with SPM8 and homogenizing the intensities using synthetic phantoms. This registration method was tested and validated on two datasets acquired for hippocampus subparts imaging in two different centers for a total of 34 subjects. It proved robust for both multi-slab protocols.

Uzay Emrah Emir^1,2, Margarida Julià-Sapé³, Peter Jezzard¹, Diane Hutter², Khalaf O Bushara², and Gulin Oz^2
1FMRIB Centre, University of Oxford, Oxford, United Kingdom, ²University of Minnesota, Minneapolis, Minnesota, United States, ³Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain

A metabolomics approach to analyzing in vivo MRS data might benefit substantially from ultra high field (UHF) due to the improved sensitivity and resolution. In this study, we explored the potential of a metabolomics approach to MRS by comparing patients with spinocerebellar ataxia type 1 (SCA1) to healthy controls both at 3T and 7T. Due to high spectral quality at both fields, distinct clustering with a complete separation between SCA1 and controls was achieved. The improved sensitivity and resolution at 7T enabled identification of three distinct spectral features whereas only 2 distinct features were identified at 3T.

Eleonora Maggioni^1,2, Mauro Costagli^2,3, Gianluigi Reni⁴, Anna Maria Bianchi¹, and Michela Tosetti^3
1Department of Electronics Information and Bioengineering, Politecnico di Milano, Milano, Milano, Italy, ²IMAGO7 Research Center, Pisa, Pisa, Italy, ³IRCCS Stella Maris Scientific Institute, Pisa, Pisa, Italy, ⁴Bioengineering Lab, Scientific Institute IRCCS E.Medea, Bosisio Parini, Lecco, Italy

The present abstract introduces the Minimum Intensity Snake Algorithm (MISA), an image processing method for the semi-automatic detection of borders into MR images acquired with the recently proposed Tissue Border Enhancement (TBE) Inversion Recovery (IR) technique. In TBE images the interfaces between tissues are enhanced and immediately visible, but difficult to extract with the most common histogram-based segmentation algorithms. Starting from a voxel marked by the user, the proposed method iteratively traces the curve of minimum intensity by exploiting graph theory functions. The MISA results on TBE images are promising and meet the requirements of subsequent quantitative analysis.

Joost Haarsma^1,2, Jannie P Wijnen¹, Kathy N Thakkar², Dennis WJ Klomp¹, and Bas Neggers^2
1Radiology, University Medical Centre Utrecht, Utrecht, Utrecht, Netherlands, ²Psychiatry, University Medical Centre Utrecht, Utrecht, Utrecht, Netherlands

Response inhibition has been investigated using the oculomotor search-step task. Research into the neural substrates involved in response selection tasks (like the one used in this study) has pointed towards a crucial role for the basal ganglia, which influence action largely via GABAergic neurotransmission. We therefore hypothesized a relation between GABA levels (measured using ultra high field MR-spectroscopy) in the striatum, the input node of the basal ganglia, and performance on the search step-task in healthy participants. At highest MR sensitivity, no significant correlations between GABA levels and performance on the search-step task were found in this study.

Mansi Parekh¹, Ryan Purcell², Sherveen Parivash¹, Brian Rutt¹, and Michael Zeineh^1
1Radiology, Stanford University, Stanford, CALIFORNIA, United States, ²Neuroscience, University College London, London, United Kingdom

The hippocampal hilus may have unique neuroanatomy in humans compared to monkeys and rodents, with CA3h greatly enlarged and a unique white-matter pathway called the endfolial pathway present. In this stud,y we used newly developed 7.0T whole brain imaging achieving 0.4mm isotropic images to study in vivo the anatomy of the hippocampal hilus. We validate these in vivo finding with 0.1mm isotropic excised specimen images as well as histologically using a myelin stain. The endfolial pathway is a central pathway in the hippocampus, possibly unique to humans, and poorly described. However, our methodology will allow for its study and understanding its function.

Sören Johst^1,2, Stephan Orzada^1,2, Mark E. Ladd^1,3, and Stefan Maderwald^1
1Erwin L. Hahn Institute for MRI, University Duisburg-Essen, Essen, Germany, ²Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University Duisburg-Essen, Essen, Germany, ³Medical Physics in Radiology, German Cancer Research Center (dkfz), Heidelberg, Germany

In recently published work, a turbo-FLASH sequence was modified for non-contrast-enhanced imaging of the lower extremity vessels at 7T. To reduce acquisition time, venous saturation RF pulses were applied every second TR. This led to an aliasing artifact caused by periodic signal variation due to alternating TR length. Here, theoretical flip angles for artifact reduction depending on both TRs were calculated and compared to experimental data from phantom measurements. Due to the inhomogeneous transmit field at 7T, the artifact could not be suppressed completely and thus additional methods such as special k-space ordering may need to be implemented.

Xiufeng Li¹, Pierre-Francois Van de Moortele¹, Kamil Ugurbil¹, and Gregory J Metzger^1
1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States

Previous applications of ASL in cardiac perfusion imaging indicated low perfusion signal to noise ratio (SNR) and large dominant temporal errors at 3T. Ultra high field 7T has the potential to provide higher SNR for ASL perfusion imaging due to greatly increased blood T1 and imaging SNR. To explore the benefits of 7T for ASL cardiac perfusion imaging, studies were performed on both 3T and 7T with results indicating that 7T could improve cardiac ASL perfusion SNR.

Oliver Kraff¹, Karsten Beiderwellen^1,2, Anja Fischer², Stephan Orzada^1,2, Stefan Maderwald¹, Mark E Ladd^1,3, Thomas C Lauenstein², and Lale Umutlu^2
1Erwin L. Hahn Institute for MRI, University Duisburg-Essen, Essen, Germany, ²Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, Essen, Germany, ³Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany

MRA is one of the applications that may benefit dramatically from the increase of the magnetic field strength to 7T. The aim of this study is the evaluation of the diagnostic quality of renal MRA at 7T in non-contrast-enhanced TOF versus contrast-enhanced FLASH imaging under reduction of contrast agent dosage to one-half and one-quarter of the standard dosage. 15 healthy volunteers (9f, 6m) were included in this study. The possibility to perform high-quality native and low-dose vessel imaging may be of high clinical importance for patients with renal insufficiency.

Alexander J.E. Raaijmakers¹, Hamza El Aidi¹, Maarten Versluis², Andrew Webb², Hildo J. Lamb³, Peter R. Luijten¹, Cornelis A.T. van den Berg⁴, and Tim Leiner^1
1Radiology, UMC Utrecht, Utrecht, Utrecht, Netherlands, ²J.C. Gorter Institute, LUMC, Leiden, Netherlands, ³Radiology, LUMC, Leiden, Netherlands,⁴Radiotherapy, UMC Utrecht, Utrecht, Netherlands

Coronary MR imaging at 7.0T has the potential to improve imaging quality. The objective of this work is to demonstrate the feasibility of comprehensive coronary artery MR imaging at 7.0T, including all three major coronary arteries. Imaging is performed using a novel 8-channel transmit receive array with modified dipole antennas. The LCX and LAD have been imaged successfully in respectively 4 and 5 out of 7 cases; the RCA in 5 out of 5. Image quality is good while there is even room for improvement. The results provide a promising showcase that coronary artery imaging is feasible at 7 Tesla.

Marek Chmelik¹, Michal Povazan¹, Martin Krššák^1,2, Stephan Gruber¹, Ladislav Valkovic¹, Siegfried Trattnig¹, and Wolfgang Bogner^1
1High Field MR Centre, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria, Austria, ²Division of Endocrinology and Metabolism, Department of Internal Medicine III, Medical University of Vienna, Austria

The feasibility of commonly used ³¹P-MRS localization techniques (1D-ISIS, 3D-ISIS, 2D CSI and 3D CSI; n=9) that are suitable for both localized MRS of focal lesions and semi-localized MRS for use in diffuse pathologies in the human liver was demonstrated at 7T. Liver ³¹P MRS at 7T provides improved data quality in acceptable measurement time. All methods provided data with high spectral quality regarding signal to noise, small linewidth and low CRLB(<11%). Voxel volume and acquisition time corrected SNR was similar for all the methods.

Junghwan Kim^1,2, Kyongtae Ty Bae^1,2, Narayan Krishnamurthy¹, Tiejun Zhao³, Hoby Hetherington², and Tamer S. Ibrahim^1,2
1Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States, ²Radiology, University of Pittsburgh, Pittsburgh, PA, United States,³Siemens Medical Solutions, Inc, Pittsburgh, PA, United States

We tested the feasibility of Proton/Lithium MR imaging using a dual-tuned RF array. To evaluate the coil performance, SNR at 1) three ROIs, 2) different thicknesses and 3) different concentrations were measured. SNR was ~90-180 at different ROIs and spectrum at different concentration was compared using 2D CSI sequence.

Konstantinos Papoutsis^1,2, Linqing Li¹, Jamie Near³, Stephen J Payne², David Edwards², and Peter Jezzard^1
1FMRIB Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom, ²Department of Engineering Science, University of Oxford, Oxford, United Kingdom, ³Centre d'Imagerie Cérébrale, McGill University, Montreal, Quebec, Canada

A 2-channel transmit/receive neck coil has been constructed for carotid artery vessel wall imaging at 7 Tesla. The coil comprises 2 elements operating in parallel transmit and receive via a custom T/R switch. The coil has been evaluated for RF safety via estimation of worst case SAR with electromagnetic simulations and temperature measurements in meat phantoms. A black blood FLASH sequence with DANTE preparation pulses has been implemented for evaluation of the benefits of the ultra high field with promising results. The resolution achieved in a male subject was 0.6mm isotropic with 4 min acquisition time.

Alexander J.E. Raaijmakers¹, Tim van Daalen¹, Ingmar Voogt¹, Michel Italiaander², Peter R. Luijten¹, Cornelis A.T. van den Berg³, and Dennis W.J. Klomp^1
1Radiology, UMC Utrecht, Utrecht, Utrecht, Netherlands, ²MR Coils B.V., Drunen, Netherlands, ³Radiotherapy, UMC Utrecht, Utrecht, Utrecht, Netherlands

Surface transmit arrays provide great advantages for ultra-high field imaging in terms of efficiency. More recently, dipole antennas have improved their performance considerably. However, their rigid structure does not always allow them to adapt to the body curvature. This work presents a dipole antenna prostate array that consists of foam and flexible PCB. The structure always adapts well to the shape of the subject. Matching was shown to be acceptable for three different subjects while coupling between elements is minimal. Imaging performance was characterized by a T2w TSE prostate image.

Adnan Trakic¹, Jin Jin¹, Mingyan Li¹, Darryl McClymont¹, Ewald Weber¹, Hector Sanchez Lopez¹, Miguel Fuentes¹, Feng Liu¹, and Stuart Crozier^1
1The School of Information Technology and Electrical Engineering, The University of Queensland, Brisbane, QLD, Australia

This new study explores the feasibility of using a single-channel mechanically Rotating RF Coil (RRFC) for flip angle (FA) and specific absorption rate (SAR) management applications at 7T MRI. Compared to the 8-channel Parallel Coil Array, RRFC yielded a much more uniform FA distribution and a lower SAR. This initial study suggests that RRFC may be very useful in alleviating the FA and SAR issues associated with contemporary high field MRI.

Cem Murat Deniz^1,2, Ryan Brown¹, Leeor Alon^1,2, Martijn Cloos^1,2, Gene Y Cho^1,2, Graham Wiggins¹, Christopher M Collins^1,2, and Daniel K. Sodickson^1,2
1The Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, United States, ²The Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, United States

At high field strength, safety assessment of local multi-channel arrays currently relies on electromagnetic field simulations. Additional verifications of the accuracy of the simulated RF array can be performed using E-field or temperature measurements with additional probes, or with B1+ measurements. In this work, we investigated the use of MR thermometry as a validation tool of the representation of the RF array in simulations. Our results suggest that MR thermometry is a valuable tool readily available in any MR scanner for transmit array safety assessment

Gianluigi Tiberi¹, Nunzia Fontana², Riccardo Stara³, Mark Roger Symms⁴, Agostino Monorchio², Mauro Costagli¹, Laura Biagi⁵, Mirco Cosottini⁶, and Michela Tosetti^5
1Imago7, Pisa, PI, Italy, ²Dipartimento di Ingegneria dell’Informazione, Pisa, Italy, ³Dipartimento di Fisica, Pisa, Italy, ⁴General Electric ASL Scientist (EMEA), Pisa, Italy, ⁵IRCCS Stella Maris, Pisa, Italy, ⁶Dipartimento di Neuroscienze, Pisa, Italy

In this study we investigated the effects of the load size on the maximum local SAR at 7T. Specifically, we resorted to: i) 3D full wave numerical electromagnetic simulations for analyzing a surface loop loaded with anatomic human calves models; ii) 2D analytical approach for analyzing a volume resonator loaded with homogeneous cylindrical phantoms having average tissue dielectric properties. In both cases we noticed that the maximum local SAR decreases with decreasing load size: this holds true if the RF magnetic fields (B1+) for the different load sizes are scaled so to achieve the same slice average value of 1ìT.

Yujuan Zhao¹, Tiejun Zhao², Narayanan Krishnamurthy¹, and Tamer S. Ibrahim^1
1University of Pittsburgh, Pittsburgh, PA, United States, ²Siemens Medical Solutions, Pittsburgh, PA, United States

The inhomogeneous distribution of the excitation field (B1+) and the potential rise in local RF absorption (SAR) are two of the major obstacles hampering potential clinical applications of the ultrahigh field human MRI (7T and higher.) Ideally, the “quadrature” excitation construction will give the most efficient B1+ field and the destruction of the central E fields will generate less SAR (less power absorptions. While there could be many different optimization solutions (we include many of which into several of our in-vivo studies) for the RF excitation that achieve a very similar fidelity to the targeted excitation pattern (homogenous B1+ field), minimizing the local SAR and maximizing the B1+ efficiency are two of the most important constraints of the optimization procedure.

Zihao Zhang^1,2, Dehe Weng³, Jing An³, Bo Wang¹, Yan Zhuo¹, Xiaohong Joe Zhou⁴, and Rong Xue^1
1State Key Lab of Brain and Cognitive Science, Beijing MR Center for Brain Research, Institute of Biophysics, Chinese Academy of Sciences, Beijing, Beijing, China, ²Graduate School, University of Chinese Academy of Sciences, Beijing, Beijing, China, ³Siemens Shenzhen Magnetic Resonance Ltd., Shenzhen, Guangdong, China, ⁴Dept. of Radiology, Center for MR Research, University of Illinois, Chicago, Illinois, United States

Time-Of-Flight (TOF) MR angiography has exhibited considerable advantages at very-high and ultra-high magnetic fields. However, the tracking saturation pulse to suppress venous signals in TOF is commonly omitted at 7T to stay within the SAR limit, leading to venous contamination in MIP angiograms. This study reduces the duty cycle of saturation pulse by introducing segmented TOF. Comparing with the conventional TOF sequence, the new sequence reduces the total number of saturation pulses and the SAR values considerably. As a result, the advantages of 3T and 7T MR angiography are better realized to improve the angiogram quality.

Douglas A. C. Kelley¹, Graeme C McKinnon², Laura Sacolick³, Daniel B Vigneron⁴, and Sarah J Nelson^4
1Neuro Apps and Workflow, GE Healthcare, Corte Madera, CA, United States, ²MR Physics, GE Healthcare, Waukesha, WI, United States, ³MR, GE Healthcare, Muenchen, Germany, ⁴Radiology & Biomedical Imaging, UCSF, San Francisco, CA, United States

A Zero Echo Time (ZTE) sequence compatible with conventional phased array coils was implemented and optimized at 7T for brain imaging with more uniform T1 contrast and high sensitivity while retaining sensitivity to fast relaxing spins. Details of the implementation and optimization are provided along with images from phantoms and normal volunteers. Comparison is provided to a conventional 3D inversion prepared gradient echo imaging sequence of equal scan time. An additional feature of the sequence is that it generates very low levels of acoustic noise.

Manojkumar Saranathan¹, Thomas Tourdias¹, May Han², and Brian K Rutt^1
1Department of Radiology, Stanford University, Stanford, CA, United States, ²Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, United States

The purpose of this work was to optimize MP-RAGE imaging at 7T. Two regimes- a conventional cerebral spinal fluid nulled (CSFn) and a white-matter nulled (WMn) MP-RAGE for imaging cortical lesions and thalamus-were optimized for scan time, SNR and contrast efficiency. The effect of α and TR on image blurring was modeled and validated. A novel 2D-centric radial fanbeam (RFB) k-space segmentation scheme was used for reducing scan times. Finally, healthy human subjects and patients with multiple sclerosis (MS) were scanned at 7T to demonstrate novel lesion detectability.