Contrast & Non-contrast MRA
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Thursday 10 May 2012
Room 201  10:30 - 12:30 Moderators: Thorsten Bley, Rola Saouaf

10:30 0524.   Three-Station Time-Resolved 3D Bolus Chase MRA with a Single Injection of Contrast Material
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. Riederer1
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 Eggers4
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.

10:54 0526.   MRA for primary diagnosis of pulmonary embolism from the Emergency Department: Outcomes analysis of 190 symptomatic patients at One year
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 Reeder1
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.

11:06 0527.   
Steady State MRA Techniques With a Blood Pool Contrast Agent Improve Visualization of Pulmonary Venous Anatomy Compared with Time Resolved MRA Pre and Post Catheter Ablation in Atrial Fibrillation
Rahul Rustogi1, Mauricio Galizia1, Jeremy Collins1, Darshit Thakrar1, and James Carr1
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.

11:18 0528.   
Clinical evaluation of peripheral non-contrast enhanced MR angiography (NCE-MRA) using steady-state free precession (SSFP) and flow sensitive dephasing (FSD) in diabetes
Na Zhang1, Zhaoyang Fan2, Fei Feng3, Pengcheng Liu4, Xin Liu1, Dehe Weng5, Renate Jerecic6, Yongming Dai5, Hairong Zheng1, and Debiao Li2
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£¨¡İ50%£©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.

11:30 0529.   Prospective Self-Gated Nonenhanced Magnetic Resonance Angiography
Erik J. Offerman1, Ioannis Koktzoglou1,2, Christopher Glielmi3, Anindya Sen1, and Robert R. Edelman1,4
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.

11:42 0530.   
Non-contrast virtual bolus angiography with sub-second temporal resolution
Ek T Tan1, Vincent B Ho2,3, James F Glockner4, Daniel V Litwiller5, Christopher J Hardy1, and Thomas K Foo1
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.

11:54 0531.   Simultaneous Non-contrast Angiography and intraPlaque hemorrhage (SNAP) imaging for atherosclerotic disease evaluation
Jinnan Wang1, Peter Börnert2, Huilin Zhao3, Xihai Zhao4, Niranjan Balu5, Marina S Ferguson5, Thomas S Hatsukami5, Jianrong Xu3, Chun Yuan5, and William S Kerwin5
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.

12:06 0532.   
Non-contrast-enhanced renal and abdominal MRA using velocity-selective inversion preparation
Taehoon Shin1, Pauline W Worters2, Shreyas S Vasanawala2, Bob S Hu3,4, and Dwight G Nishimura1
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.

12:18 0533.   
Non-Contrast Enhanced Time-Resolved 4D MRA with Dynamic Golden Angle Radial Acquisition and K-Space Weighted Image Contrast (KWIC)
Yiqun Xue1, Lirong Yan2, Yoon Chung Kim2, Danny JJ Wang2, and Hee Kwon Song1
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.