Casey P. Johnson¹, Eric A. Borisch¹, Phillip J. Rossman¹, Thomas C. Hulshizer¹, Roger C. Grimm¹, Paul T. Weavers¹, James F. Glockner¹, Phillip M. Young¹, and Stephen J. Riederer^1
1MR Research Laboratory, Mayo Clinic, Rochester, MN, United States

A new method for 3D bolus chase MRA is demonstrated for imaging from the iliac arteries to the pedal arches with both high spatial and temporal resolution. The CAPR time-resolved imaging technique is used with 8x 2D SENSE and 1.8-1.9x 2D partial Fourier acceleration throughout the extended FOV to allow 1.5, 1.5, and 1.0 mm isotropic resolution and 2.5, 2.5, and 5.2 sec frame times at the abdomen-pelvis, thigh, and calf-foot stations, respectively. Frames at the proximal stations are reconstructed in real-time, enabling fluoroscopic tracking of the contrast bolus, triggering of table advance, and only one contrast injection per exam.

Tim Leiner¹, Bastiaan Versluis², Liesbeth Geerts³, Eveline Alberts³, Jeroen Hendrikse¹, Evert Jan Vonken¹, and Holger Eggers^4
1Department of Radiology, Utrecht University Medical Center, Utrecht, Netherlands, ²Department of Radiology, Maastricht University Medical Center, Maastricht, Netherlands, ³Clinical Science Department, Philips Healthcare, Best, Netherlands, ⁴Sector Imaging Systems, Philips Research, Hamburg, Germany

The feasibility of single contrast medium dose (0.1 mmol/kg) subtractionless dual-echo Dixon imaging for first-pass contrast-enhanced fat-suppressed peripheral MRA is demonstrated in 17 patients with suspected peripheral arterial disease. Vessel to background contrast was uniformly better when compared to conventional subtraction based approaches. Despite the requirement to measure two echoes per TR the proposed method is compatible with high-spatial resolution acquisitions during initial arterial passage of contrast material due to high parallel imaging factors. Dual-echo Dixon peripheral MRA represents substantial timesavings over the conventional subtraction-based approach to peripheral MRA and avoids potential subtraction misregistration artifacts.

Mark L Schiebler¹, Scott K Nagle¹, Christopher J. François¹, Michael Repplinger², Azita Hamedani², Kang Wang³, Karl Vigen¹, Jean H Brittain³, Thomas M Grist¹, and Scott B Reeder^1
1Radiology, UW-Madison, Madison, WI, United States, ²Emergency Medicine, UW-Madison, Madison, WI, United States, ³General Electric Healthcare, Applied Science Laboratory, Madison, WI, United States

Pulmonary MRA (MRA-PE) can be used for the accurate diagnosis of pulmonary embolism (PE). We present our clinical experience of MRA-PE for the primary diagnosis of PE in 190 symptomatic patients referred from the emergency department. We employed a one-year follow up as the surrogate parameter for efficacy. In contrast to PIOPED III, 96.3% of our exams were of diagnostic quality; indicating excellent technical success. There were no subsequent PE’s found in MRA-PE negative patients at their one year follow up. High quality single breath hold whole lung MRA for PE is an effective alternative to CTA.

Rahul Rustogi¹, Mauricio Galizia¹, Jeremy Collins¹, Darshit Thakrar¹, and James Carr^1
1Radiology, Northwestern University Feinberg School of Medicine, Chicago, IL, United States

Time resolved MRA is advantageous in the pulmonary circulation with its rapid arteriovenous transit time, allowing acquisition of pure pulmonary venous phase images, however increased temporal resolution comes at the cost of decreased spatial resolution. Proposed use of steady state MRA (inversion recovery FISP and FLASH sequences) with a blood pool agent can obviate the need to perform bolus timing while significantly increasing spatial resolution. Accurate assessment of anatomical variants such as early branching pattern of pulmonary veins before ablation and ostial stenosis post-ablation, is vital for catheter based ablation therapies for patients with atrial fibrillation.

Na Zhang¹, Zhaoyang Fan², Fei Feng³, Pengcheng Liu⁴, Xin Liu¹, Dehe Weng⁵, Renate Jerecic⁶, Yongming Dai⁵, Hairong Zheng¹, and Debiao Li^2
1Paul C. Lauterbur Research Centre for Biomedical Imaging, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China, ²Cedars Sinai Medical Center and University of California, Los Angeles, CA, United States, ³Department of Radiology, Peking University Shenzhen Hospital, Shenzhen, Guangdong, China, ⁴3Department of Radiology, Peking University Shenzhen Hospital, ⁵Siemens Healthcare, Shanghai, China, ⁶Siemens Healthcare

A novel peripheral non-contrast enhanced MR Angiography (NCE-MRA) using SSFP and flow-sensitive dephasing (FSD) was evaluated for detecting peripheral arterial disease in diabetes. Forty-five patients underwent contrast enhanced MRA (CE-MRA) and NCE-MRA in calf and foot on a 1.5T MR system. Image quality and significant arterial stenosis£¨¡Ý50%£©was assessed by two experienced radiologists. The technique demonstrated a comparable percentage of diagnostic arterial segments and image quality with CE-MRA, and a high diagnostic accuracy for detecting significant arterial stenosis. It can be used as an alternative method for the detection of lower-extremity arterial disease in diabetic patients.

Erik J. Offerman¹, Ioannis Koktzoglou^1,2, Christopher Glielmi³, Anindya Sen¹, and Robert R. Edelman^1,4
1Radiology, NorthShore University HealthSystem, Evanston, IL, United States, ²Pritzker School of Medicine, University of Chicago, Chicago, IL, United States, ³Siemens Healthcare, Chicago, Illinois, United States, ⁴Feinberg School of Medicine, Northwestern University, Chicago, IL, United States

ECG gating is required by most nonenhanced MRA techniques however it is subject to interference from gradient switching and radiofrequency pulses. The presented method avoids ECG gating by prospectively triggering image acquisition using a reference-less phase contrast navigator to detect blood flow acceleration during systole. The method was evaluated in QISS MRA with contrast, CNR, and image quality measurements performed in eight volunteers. Self-gated QISS triggered with 99% accuracy. All measurements found no significant difference between self-gated and ECG-gated QISS MRA (p > 0.05). Image quality with pulse gating was inferior. Self-gated NATIVE SPACE was demonstrated in a single subject.

Ek T Tan¹, Vincent B Ho^2,3, James F Glockner⁴, Daniel V Litwiller⁵, Christopher J Hardy¹, and Thomas K Foo^1
1GE Global Research, Niskayuna, NY, United States, ²Uniformed Services University of the Health Sciences, Bethesda, MD, United States, ³Walter Reed National Military Medical Center, Bethesda, MD, United States, ⁴Mayo Clinic, Rochester, MN, United States, ⁵GE Healthcare, Rochester, MN, United States

A novel dynamic virtual bolus (DVB) method that does not require the administration of gadolinium-chelate contrast media was demonstrated. Using cine phase-contrast acquisition, the velocity field was integrated and deciphered into a bolus signal for each time frame or cardiac phase. The typical result from DVB of the peripheral vessels was a movie with large FOV, long time-course (10 or more seconds) with high temporal resolution of 55 msec. The bolus progression as well as arterial pulsatility is well-visualized during systole and diastole. In time-trial simulations, sub-second accuracies were recorded. The algorithm was region-based to negotiate complex vascular trees and small vessels.

Jinnan Wang¹, Peter Börnert², Huilin Zhao³, Xihai Zhao⁴, Niranjan Balu⁵, Marina S Ferguson⁵, Thomas S Hatsukami⁵, Jianrong Xu³, Chun Yuan⁵, and William S Kerwin^5
1Philips Research North America, Briarcliff Manor, NY, United States, ²Philips Research Europe, ³Renji Hospital, ⁴Tsinghua University, ⁵University of Washington

Simultaneous Non-contrast Angiography and intraPlaque hemorrhage (SNAP) imaging was proposed and validated for detecting luminal stenosis and intraplaque hemorrhage in atherosclerosis patients in 1 scan. SNAP provides robust MRA delineation and sensitive hemorrahge detection when compared to the current techniques. It has the potential to become the first line imaging methods in clinics.

Taehoon Shin¹, Pauline W Worters², Shreyas S Vasanawala², Bob S Hu^3,4, and Dwight G Nishimura^1
1Electrical Engineering, Stanford University, Stanford, CA, United States, ²Radiology, Stanford University, ³Palo Alto Medical Foundation, Palo Alto, CA, United States, ⁴Heart Vista Inc., Palo Alto, CA, United States

Inflow slab-selective (SS) inversion-recovery (IR) 3D imaging has been widely used for non-contrast-enhanced (NCE) renal MR angiography, but with limited craniocaudal coverage due to the usability of upstream arterial blood only. We propose a novel NCE MRA method that allows visualization of renal and abdominopelvic arteries over a large field-of-view. This is achieved by employing a velocity-selective inversion preparation that preserves arterial blood within the imaging volume while inverting background tissues. The capability of the proposed method to depict various abdominal arteries is demonstrated in-vivo with a comparison to the SS IR method.

Yiqun Xue¹, Lirong Yan², Yoon Chung Kim², Danny JJ Wang², and Hee Kwon Song^1
1Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States, ²Neurology, UCLA, Los Angeles, California, United States

This work describes a new method for non-contrast enhanced time-resolved dynamic MRA (dMRA) utilizing single- and multi-shot dynamic radial acquisition with golden angle view increment and k-space weighted image contrast (KWIC). The reconstructed 4D dMRA data set demonstrated a high quality, high temporal resolution dynamic series without apparent temporal blurring, yielding results comparable to standard Cartesian based dMRA approaches, but in a fraction of the scan time.