Jackie Leung¹, Arun Mohanta¹, Amir Behpour^1,2, Neil Sokol², and Andrea Kassner^1,2
1Diagnostic Imaging, Hospital for Sick Children, Toronto, Ontario, Canada, ²Medical Imaging, University of Toronto, Toronto, Ontario, Canada

Transcranial Doppler ultrasonography (TCD) and phase contrast MR angiography (PCMRA) are both capable of assessing cerebral blood flow velocity changes in response to a vasoactive stimulus. TCD is widely used because it is inexpensive and accessible, despite concerns about measurement variability. PCMRA does not have such limitations. However, previous attempts to correlate TCD and PCMRA readings in the brain have produced inconsistent results. We propose to utilize a reproducible CO2 stimulus with precise end-tidal PCO2 and PO2 targeting to compare blood flow velocities changes in the middle cerebral artery using both modalities.

Mamoru Takahashi¹, Yasuo Takehara², Hiroyasu Takeda², Masaki Terada³, Haruo Isoda⁴, Tetsuya Wakayama⁵, Atsushi Nozaki⁵, Toshiyuki Shimizu⁶, Marcus Alley⁷, Roland Bammer⁷, Norihiko Siiya², Norihiro Tooyama⁸, Katsutoshi Ichijo⁸, and Harumi Sakahara^2
1Radiology, Seirei Mikatahara General Hospital, Hamamatsu, Shizuoka, Japan, ²Hamamatsu University School of Medicine, ³Iwata City Hosipital, ⁴Nagoya University School of Health Sciences, ⁵GE Helthcare Japan, ⁶R's Tech Co., ⁷Stanford University School of Medicine, ⁸Seirei Mikatahara General Hospital

Hemodynamic patterns of the abdominal aorta were assessed with streamlines and pathlines, and wall shear stress was analyzed on color coded cine maps postprocessing 4D Flow data. As a result, kinking aorta suffered vortex or turbulent flow at the inner curvature of the aorta mainly during the early-diastole and this resulted in significantly low wall shear stress of the corresponding portion, while non-kinking aorta did not. Kinks of the abdominal aorta create vorticity or turbulence of the blood flow at the inner curvature of the kinking aorta,�@which may have further atherogenic effect of the corresponding aortic wall.

Anders Nilsson¹, Karin Markenroth Bloch^1,2, and Freddy Ståhlberg^1,3
1Dept. of Medical Radiation Physics, Lund University, Sweden, ²Clinical Sciences, Philips Healthcare, Lund, Sweden, ³Dept. of Diagnostic Radiology, Lund University, Sweden

Conventional implementation of phase contrast sequences determines the velocity encoding sensitivity (Venc) from the maximal velocity in the complete cardiac cycle. In heart phases with slow flow, the Venc is therefore much higher than needed. By optimizing the Venc to the specific area of interest, it has been shown that the noise could be lowered substantially. In this work, we investigate the potential benefits of a 4D phase-contrast sequence with variable velocity encoding throughout the cardiac cycle, with respect to blood flow visualizations.

Aurelie Picquot¹, Francesco Santini², Jelena Bock³, Philippe Reymond¹, Eleonora Fonari⁴, Bryn Andrew Martin¹, and Nikos Stergiopulos^1
1Laboratory of Hemodynamics and Cardiovascular Technology, Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland, ²Radiological Physics, University of Basel Hospital, Switzerland, ³Department of Radiology, University Hospital Freiburg, Germany, ⁴Lausanne Center for Biomedical Imaging, Centre Hospitalier Universitaire Vaudois, Switzerland

CFD simulations have provided detailed information about the complex flow and pressure field within the cerebrospinal fluid system. The solutions of these simulations are sensitive to boundary conditions and thus need validation with in vivo measurements. However, validation of 3D CFD flow calculations and MRI CSF flow measurements have been limited to through plane pcMR velocity measurements. Recent advancements in MRI flow measurement technology have enabled fast measurement of the 3D velocity field within the spinal subarachnoid space, superior sagittal sinus, and ventricles of the brain. This study was focused on comparing the results between 3D CFD flow calculations and 7D MRI measurements within the aqueduct of Sylvius and the third ventricle of the brain.

Yi Wang^1,2, Edwin Estrada¹, Visali Kodali¹, and Nathaniel Reichek^1,3
1Research, St. Francis Hospital, Roslyn, NY, United States, ²Biomedical Engineering, Stony Brook University, Stony Brook, NY, United States, ³Cardiology, Stony Brook University, Stony Brook, NY, United States

Aortic pulse wave velocity is altered by normal aging, as well as vessel wall pathology. We evaluated aortic compliance and its relationship to age in normals and repeated the evaluation at 5-year followup.

Anja Lutz¹, Axel Bornstedt¹, Patrick Etyngier², Robert Manzke³, Wolfgang Rottbauer¹, G Ulrich Nienhaus⁴, and Volker Rasche^1
1University Hospital of Ulm, Ulm, BW, Germany, ²Medisys Research Lab, Philips Healthcare, Sureness, France, ³Philips Research NA, Briarcliff Manor, United States,⁴Karlsruhe Institute of Technology, Karlsruhe, Germany

Three-dimensional assessment of the myocardial contraction is gaining increasing interest e.g. for the identification of heart failure patients gaining from cardiac resynchronization therapy. For a complete understanding of the complex contraction pattern, direct velocity encoding of the myocardium appears attractive. It is the objective of this study to investigate the feasibility of volumetric whole-heart three-directional velocity encoded MRI for retrieving the complex contraction pattern of the heart. A strong variation of the radial, longitudinal and circumferential myocardial motion over different short axes regions of the heart was detected.

Xiaoli Zhang^1,2, Yu Qing Zhou¹, Mark van Doormaal¹, and R Mark Henkelman^1,2
1Mouse Imaging Centre, Hospital for Sick Children, Toronto, Ontario, Canada, ²Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada

Hemodynamic wall shear stress has been related to atherosclerosis development. However, the association between salient characteristics of flow patterns and localization of atherosclerotic lesions is still not fully understood. Our recent study has used surgical induction of aortic valve regurgitation to significantly change flow pattern and atherosclerotic plaques along the thoracic and abdominal aorta, which were normally lesion free. This study used a phase contrast MRI technique to elucidate blood flow in the aorta of control and AR mice. Retrograde flow during diastole was observed in the AR mouse.

Hung-Yu Lin^1,2, Scott B King¹, Yu Ding³, Davinder S Jassal², Patricia Gervai¹, Eilean McKenzie-Matwiy¹, Orlando P Simonetti³, Boguslaw Tomanek¹, and Ganghong Tian^1
1Institute for Biodiagnostics, National Research Council Canada, Winnipeg, Manitoba, Canada, ²Radiology, University of Manitoba, Winnipeg, Manitoba, Canada, ³Internal Medicine, The Ohio State University, Columbus, Ohio, United States

This study is to develop and demonstrate a novel phase-contrast shared velocity encoding technique using an interleaved two-slice acquisition scheme for accurate single heartbeat evaluation of pulmonary-to-systemic flow ratio (Qp/Qs).

Visali Kodali¹, Yi Wang¹, Simcha Pollack^1,2, Edwin Estrada¹, and Nathaniel Reichek^1,3
1Cardiac Imaging, Research, Saint Francis Hospital, Roslyn, New York, United States, ²St. John’s University, New York, New York, United States, ³Department of Biomedical Engineering Division of Cardiology, Stony Brook University, Stony Brook, New York, United States

Aortic pulse wave velocity is an index of aortic compliance. We evaluated Aortic pulse wave velocity by cardiac magnetic resonance imaging in normal volunteers and examined its relation to various clinical and cardiac function parameters. Age is the strongest and most consistent correlate of increased PWV. Coronary CT Calcium score strongly correlates with PWV. After adjustment for age, no other variables show significant associations with PWV. In normal subjects cardiac function parameters do not correlate with PWV.

Daeho Lee¹, Adam Bruce Kerr¹, Juan Manuel Santos², Bob Sueh-Chien Hu³, and John Mark Pauly^1
1Electrical Engineering, Stanford University, Stanford, CA, United States, ²HeartVista, Inc., Palo Alto, CA, United States, ³Cardiology, Palo Alto Medical Foundation, Palo Alto, CA, United States

The pressure gradient across cardiac valves is commonly utilized to evaluate the severity of valvular stenosis. Peak velocity is often used to derive the pressure-gradient, and more accurate estimation is possible with a localized velocity spectrum. MR Doppler has been shown to effectively acquire a spatially resolved velocity spectrum in real-time without cardiac gating thanks to resolving flow along a cylindrical pathway restricted by pencil beam excitation. The fidelity of velocity estimation is especially critical for diagnosing stenotic flow in the range of 2~3 m/s. However, off-resonance, inflow effect, and flow acceleration during readout incurs signal drop and spurious dispersion in the velocity spectrum, degrading the velocity estimation. We present a circular k-space echo-shifted interleaved acquisition method to improve the reliability of velocity estimation, especially for imaging high-velocity jets.

Thomas A Hope¹, Stephen ES Crook¹, and Michael D Hope^1
1Radiology, University of California San Francisco, San Francisco, CA, United States

Aneurysm formation status post aortic coarctation repair is associated with hypoplastic aortic arches. We utilized three-dimensional time resolved phase contrast MRI to demonstrate that there are abnormal systolic flow patterns that result in elevated wall shear stress in the regions of aneurysm formation in patients with hypoplastic aortic arches. These flow features may help explain the high incidence of aneurysm formation in this population as well as identify patients at high risk for aneurysm formation.

Iain Thomas Pierce^1,2, Peter David Gatehouse^1,2, Evi Kalodiki^3,4, Chris Lattimer^3,4, George Geroulakos^3,4, and David N Firmin^1,2
1NHLI, Imperial College London, London, United Kingdom, ²CMR Unit, Royal Brompton Hospital Trust, London, United Kingdom, ³Dept of Surgery and Cancer, Imperial College London, London, United Kingdom, ⁴Vascular Unit, Ealing Hospital, London, United Kingdom

Intermittent Pneumatic Compression is commonly used as prophylaxis for venous-thromboembolism. Previously Doppler ultrasound has been used to investigate the venous flow resulting from IPC devices. Real-time MR velocity mapping, using spiral gradient readouts, was used to monitor the anatomical and velocity changes throughout multiple IPC cycles using foot and calf cuffs together and also individually. This method measured deep venous flow in 12 subjects allowing complex flow to be visualised in two subjects and measurement from secondary deep veins present in two different subjects, both of which would not be possible using ultrasound.

Peter Speier¹, Andreas Greiser¹, Andre de Oliveira¹, Dirk Franger², and Edgar Müller^1
1Siemens AG Healthcare Sector, Erlangen, Germany, ²Freelance Software Consultant

An interactive real-time velocity encoding (venc) scout is introduced as a fast and easy way to optimize the parameters of a clinical flow measurement. The required image quality and frame rate in the phase contrast images is achieved by applying severely undersampled radial acquisition. The interactively found venc value and scan plane geometry are propagated automatically to the subsequent clinical segmented flow measurements. The method is compared against a standard segmented breath-hold venc scout.

Julia Geiger¹, Raoul Arnold², Brigitte Stiller², Mathias Langer¹, and Michael Markl^1
1Radiology and Medical Physics, University Hospital Freiburg, Freiburg, Germany, ²Pediatric Cardiology, University Hospital Freiburg, Freiburg, Germany

The aim of this study was to analyze the flow characteristics in patients after repair of tetralogy of Fallot by flow-sensitive 4D MRI. Flow acceleration, vortices and retrograde flow were successfully visualized in the pulmonary system. We detected a significant correlation between some vascular geometric parameters, particularly vessel diameter and pulmonary branching angles, and abnormal flow patterns. 4D MRI is an excellent technique to demonstrate the complexity of postoperative hemodynamics in Fallot patients.

Waltraud Brigitte Buchenberg¹, Michael Markl¹, Simon Bauer¹, Jelena Bock¹, Ramona Lorenz¹, and Bernd A. Jung^1
1Radiology, Medical Physics, University Medical Centre, Freiburg, Germany

Methods to acquire the blood flow within the cardiovascular system or the myocardial motion have already been established. However, the simultaneous acquisition of this functional information requires two different velocity sensitivities (VENC) due to the different range of velocities. Therefore, a dual VENC phase contrast sequence was implemented allowing the acquisition of blood flow and cardiac motion in a single measurement and applied to five healthy volunteers.

Jos JM Westenberg¹, Patrick JH de Koning¹, Pieter J van den Boogaard¹, Dennis Hendriksen¹, Johan HC Reiber¹, Albert de Roos¹, and Rob J van der Geest^1
1Radiology, Leiden University Medical Center, Leiden, ZH, Netherlands

In a comprehensive MRI-approach, patients with Marfan syndrome are evaluated at baseline and at two year follow up. Pulse wave velocity, assessed from two-directional velocity-encoded MRI, is locally assessed in the aorta and compared with local aortic diameter growth, assessed from contrast-enhanced MR angiography of the aorta. With this new imaging tool, normal local aortic pulse wave velocity assessed with two-directional velocity-encoded MRI predicts in 89% of the cases absence of aortic diameter growth in patients with Marfan syndrome after two years follow up.

Thanh D Nguyen¹, Mitchell Cooper², Pascal Spincemaille¹, Priscilla Winchester¹, Martin R Prince¹, and Yi Wang^1
1Radiology, Weill Cornell Medical College, New York, NY, United States, ²Biomedical Engineering, Cornell University, Ithaca, NY, United States

We propose to develop an inflow based 3D non-contrast MRA sequence using stepping thin slab acquisition for lower extremity imaging. This sequence can provide improved inflow effect compared to conventional thick slab 3D acquisition as well as better SNR with higher resolution compared to 2D acquisition. Initial results from healthy subjects demonstrated 21% higher SNR in 60% less scan time compared to conventional ECG-gated 2D time-of-flight acquisition.

Timothy SE Albert, MD¹, Erin J Kelly, PhD², Patrik Zetterlund, MD¹, Connie Luna, RT¹, Nancy Yellin, RN¹, and Mitsue Miyazaki, Ph.D.^3
1Salinas Valley Memorial Hospital Cardiovascular Diagnostic Center, Monterey, CA, United States, ²Toshiba America Medical Systems, Tustin, CA, ³Toshiba Medical Research Institute USA, Inc, Vernon Hills, IL

A clinical population with a variety of vascular disease underwent a non-contrast 3D FS-FBI MRI exam and an X-Ray angiography exam. The accuracy of FS-FBI was evaluated in the assessment of various vascular diseases compared to conventional X-Ray Angiography. Using a 25-segment model blinded analysis of FBI images and DSA images, both image quality (poor-1; good-2; excellent-3) and stenotic severity (Non Diagnostic (ND), 0-25%, 26-50%, 51-75%, 76-99%, total occlusion) were compared. Overall clinical accuracy revealed a sensitivity of 0.90, specificity 0.94, positive predictive value 0.81, and negative predictive value of 0.97. In comparison to DSA, FBI shows high clinical accuracy.

Zhaoyang Fan^1,2, Xiangzhi Zhou², Xiaoming Bi³, Sven Zuehlsdorff³, Rohan Dharmakumar^1,2, James Carr², and Debiao Li^1,2
1Cedars-Sinai Medical Center, Los Angeles, California, United States, ²Northwestern University, Chicago, Illinois, United States, ³Siemens Healthcare, Chicago, Illinois, United States

Flow sensitization imparted by the flow-sensitive dephasing (FSD) preparation is essential for FSD-prepared noncontrast MRA, and its strength can be measured by the first-order gradient moment, m1. Incomplete delineation of arterial segments may result from a suboptimal m1. The optimal m1, however, is subject and artery specific. The aim of this work was to systematically investigate the utility of a 2D m1-scouting method for improving imaging quality of 3D FSD MRA. From 10 healthy subjects and 1 patient, significant increases in artery SNR and artery-vein CNR on MRA’s were obtained using this optimization procedure, which potentially help enhance diagnostic confidence.

Ruth P Lim¹, Zhaoyang Fan², Manjil Chatterji³, Amanjit Baadh¹, Iliyana Atanasova¹, Pippa Storey¹, Danny C Kim¹, Sooah Kim¹, Philip Hodnett¹, Afshan Ahmad¹, David Stoffel¹, James S Babb¹, Daniel Kim¹, Qun Chen¹, Jian Xu⁴, Debiao Li^2,5, and Vivian S Lee^1,5
1Radiology, NYU Langone Medical Center, New York, NY, United States, ²Radiology, Cedars-Sinai Medical Center and UCLA, Los Angeles, California, United States,³Radiology, Mt Sinai School of Medicine, New York, NY, United States, ⁴Siemens Healthcare, New York, NY, United States, ⁵Co-Senior Author

Slow arterial flow in the below-knee vessels is challenging for ECG-gated flow-dependent non-contrast-enhanced MRA techniques. We evaluate the performance of variable (VFA MRA) and constant (CFA MRA) flip angle fast spin echo MRA, and flow sensitive dephasing prepared steady state free precession MRA (FSD MRA) in a clinical population. Our results show comparable accuracy between the three sequences, with gadolinium-enhanced MRA as the reference standard. Image quality was highest for FSD-MRA, and fast diastolic flow was problematic for VFA MRA due to flow dephasing in diastole.

William W. Orrison Jr. MD, MBA^1,2, Erin J. Kelly, PhD³, Denise Moreau, RT ³, Cayce J. Roach^4,5, and Eric H. Hanson MD, MPH^4,5
1CHW Nevada Imaging Company, Las Vegas, NV, United States, ²Touro University Nevada, Henderson, NV, United States, ³Toshiba America Medical Systems, Tustin, CA,⁴University of Nevada Las Vegas, ⁵Advanced Medical Imaging and Genetics (Amigenics)

Three-dimensional time-of-flight is now commonly used in routine magnetic resonance angiography studies of the neck, however there are limits to its temporal and spatial resolution, which contrast-enhanced protocols have addressed. The utility of Time-SLIP to produce bright blood 3D angiograms of the carotid arteries has been under investigation. However, the high flow speed of blood through the carotid arteries can contribute to poor image quality in combination with suboptimal tag placement and BBTI selection along with poor cardiac synchronization. This optimization study served as an initial feasibility study for non-contrast Time-SLIP angiography of the carotid arteries.

Yi Wang^1,2, Karl Diedrich², Glen Morrell², Allison Payne², and Dennis L. Parker^1,2
1Bioengineering, University of Utah, Salt Lake City, UT, United States, ²Radiology, Utah Center for Advanced Imaging Research, Salt Lake City, UT, United States

Breast tumor growth is highly dependent on angiogenesis. Visualization of the breast vasculature helps assisting pre-surgical staging, treatment planning, detection of tumor reoccurrence and post-treatment evaluation in breast cancer management. For example, in Magnetic Resonance guided High-Intensity Focused Ultrasound, treatment planning and control would be improved by characterizing the vascular distribution around the target lesions and including the resulting convective effects in the appropriate models. Knowledge of the vasculature is also useful at the pre-treatment planning stage where an accurate segmentation of the treatment volume on a voxel-by-voxel basis is desired. Even though contrast-enhanced MRI has becoming a standard tool for breast cancer diagnosis, the association between contrast injection and the development of nephrogenic systemic fibrosis has raised concern, especially for patients with renal failure. To reduce these concerns, non-contrast enhanced breast vessel imaging has been investigated using a peripheral pulse gate-triggered half-Fourier turbo spin echo sequence. In this work, an untriggered variable flip angle turbo spin echo sequence was explored as a non-contrast flow-independent MR angiography technique to achieve breast vasculature imaging.

Jian Xu^1,2, Kellyanne Mcgorty¹, Ruth Lim¹, Mary Bruno¹, Monvadi Srichai¹, Daniel Kim¹, and Daniel Sodickson^1
1Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, NY, United States, ²PolyTechnic Institute of NYU and Siemens Medical Solutions USA Inc., New York, NY, United States

ECG-triggered CE-MRA of the thoracic aorta is challenging, due to competing demands of high spatial resolution and high temporal resolution within a breath-hold (BH). ECG-triggered NC-MRA is an alternative method for patients with poor intravenous access or contraindications to gadolinium administration without subtraction. ECG-triggered NC-MRA based on T2-prepared and fat suppressed balanced steady state free precession imaging with navigator gating has been shown to produce good image quality, but can take approximately 10 minutes. We propose to perform single BH ECG-triggered NC-MRA of the thoracic aorta using highly accelerated parallel imaging and compare it against ECG-triggered CE-MRA.

Onur Ozyurt¹, Ann-Kathrin Homagk², Michael Bock², and Cengizhan Ozturk^1
1Institute of Biomedical Engineering, Bogazici University, Istanbul, Turkey, ²Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany

In dynamic angiography, inflow of labeled blood to the target volume is imaged at various delay times. In this study, using a variable duration Pseudo-Continuous Arterial Spin Labeling (pCASL) for each inflow time is proposed and utilized in a dynamic angiography study at 7T.

Masanobu Nakamura¹, Masami Yoneyama¹, Tomoyuki Okuaki¹, Takashi Tabuchi¹, Atsushi Takemura², Makoto Obara², and Junko Ogura^1
1Medical Satellite Yaesu Clinic, Chiyoda-ku, Tokyo, Japan, ²Philips Electronics Japan, Tokyo, Japan

Non-contrast MRA with spin-labeling technique which discriminates arteries from veins, simultaneously suppressing signals from surrounding tissues, has been applied for exploring the renal artery. Currently available techniques for non-contrast MRA, however, enable only to gain static, single-frame images. Recently we have proposed 3D volumetric non contrast time-resolved MRA technique termed Contrast inherent inflow enhanced multi phase angiography in renal artery (CINEMA-RENAL). CINEMA-RENAL sequence was performed combining Look-Locker techniques with 3D segmented T1-weighted gradient echo sequence. Radial 3D stack-of-stars acquisition was used to diminish the motion artifacts due to breathing. CINEMA -RENAL can extract the blood flow in the renal artery at an interval of 100 ms and thus permitted us to observe vascular construction in full by preparing MIP images of axial, coronal, and sagittal acquisitions. CINEMA enables to achieve ``four dimensional`` images without contrast agents.

Marcelo E Andia¹, and Rene M Botnar^1
1Division of Imaging Sciences and Biomedical Engineering, Kings College London, London, United Kingdom

In this work we present a new ASL approach for non-enhanced MRA without the need of subtraction. Triple inversion recovery TIR-ASL exploits the ability of the Nonselective Double Inversion-Recovery sequence to null background signal while maintaining the signal in labeled blood using a regional inversion pulse.

Manojkumar Saranathan¹, Pauline W Worters¹, and Shreyas Vasanawala^1
1Radiology, Stanford University, Stanford, CA, United States

Nephrogenic systemic fibrosis (NSF) concerns associated with Gadolinium based contrast agents have spurred a resurgence in non-contrast enhanced MR Angiography (MRA) methods. Balanced steady state free precession (b-SSFP) imaging [1-3], due to its high SNR/CNR and short scan times, has been successful in coronary and renal angiography. Most current methods use respiratory gating which performs poorly during irregular breathing/sleep apnea. We propose a 3D b-SSFP-Dixon technique with a novel k-space segmentation scheme for breath-held (BH) non-contrast renal MRA without compromising coverage or spatial resolution. The sequence was tested on healthy subjects as well as patients.

Iliyana P Atanasova^1,2, Daniel Kim¹, Ruth P Lim¹, Pippa Storey¹, and Vivian S Lee^1
1New York University, New York, New York, United States, ²Columbia University, New York, New York, United States

A new non-contrast MRA pulse sequence was developed using 4 inversion-recovery (IR) pulses and 3D b-SSFP readout to provide complete coverage from renal to external iliac arteries with excellent background suppression. Respiratory triggered, non-contrast angiograms were obtained in four volunteers and one patient referred for contrast-enhanced MRA. In all subjects, MRAs exhibited excellent arterial conspicuity from the renal to the external iliac arteries with optimal background suppression. Infrarenal aortic atherosclerosis was well-visualized in the patient in good agreement with CE MRA. The new NC MRA pulse sequence provides high spatial resolution arteriograms within clinically feasible scan times of 6 min.

Mitsue Miyazaki^1,2, Yuichi Yamashita², Andrew Wheaton¹, Wayne Dannels¹, Robert Anderson¹, Leping Zha¹, and Satoshi Sugiura^2
1Toshiba Medical Research Institute USA, Vernon Hills, IL, United States, ²Toshiba Medical Systems, Otawara, Tochigi, Japan

Despite the recent advancements in 3T, non-contrast MRA faces many problems such as a specific absorption rate (SAR) and B1 inhomogeneity. The B1 wavelength effect caused by conventional quadrature RF transmission makes shading or nonuniform signal intensity unavoidable, especially in abdominal and peripheral MRA. In this study, we have adjusted the pulse sequences to lower SAR and addressed the signal shading issue by applying multi-phase RF transmission. In a result, multi-phase RF transmission sufficiently mitigates the B1-related signal shading issue for MRA.

Jörg Mauch¹, Michael Markl¹, Christoph Haller², Zoran Stankovic¹, Mathias Langer¹, and Julia Geiger^1
1Radiology, Medical Physics, University Medical Center, Freiburg, Germany, ²Cardiovascular Surgery, University Medical Center, Freiburg, Germany

The purpose of this study was to employ flow-sensitive 4D MRI for the characterization and quantification of aorto-iliac hemodynamics in patients with infrarenal abdominal aortic aneurysms. Compared to healthy volunteers, patients showed a more heterogeneous distribution of flow and demonstrated substantial flow deceleration during passage through aneurysm and sudden flow acceleration distal to the aneurysm in the proximal iliac arteries. Quantitative analysis revealed significant changes in peak velocities, total flow, and flow distribution to the left and right iliac arteries. The magnitude and extent of such alterations may thus be an indicator of aneurysm progression or onset of thrombosis.

yigang pei¹, and daoyu hu^2
1Department of Radiology, Tongji Hospital,Tongji Medical College,Huazhong University of Science and Technology, wuhan, Hubei, China, People's Republic of, ²Department of Radiology, ongji Hospital,Tongji Medical College,Huazhong University of Science and Technology, wuhan, Hubei, China, People's Republic of

Doppler sonography, MDCTV and CE-MRV scan are often used to diagnose renal vein thrombosis for renal cell carcinoma patients or evaluate renal venous system for kidney transplant patients and donors. Doppler sonography is a non-invasive and easy method, but the results are operator dependant. CE-MRV and MDCTV can show clearly the presence of tumor thrombus in inferior vena cava with renal cell carcinoma, but they are depending on Gd or iodine contrast mediums. The contrast enhanced technique has its limitations: 1: may cause nephrogenic systemic fibrosis (NSF) or contrast-Induced Nephropathy; 2: a relatively expensive examination; 3: the arterial contamination. So, in our study, a new non-contrast-enhanced MR venography (a SLEEK technique) was developed to delineate the venous spread of RCC.

Jason K Mendes¹, and Dennis L Parker^1
1University of Utah, Salt Lake City, UT, United States

Turbo spin echo (TSE or FSE) is an important technique in the discrimination of atherosclerotic plaque components such as hemorrhage, disrupted fibrous cap, lipid/necrotic core, calcification and ulceration. To distinguish between stationary tissue and flowing blood, several techniques such as Double Inversion Recovery (DIR), Quadruple Inversion Recovery (QIR) or Motion-Sensitized Driven-Equilibrium (MDSE) have been proposed These suppression techniques involve various combinations of inversion pulses over a large volume outside the slice(s) of interest. This prevents efficient interleaving of multiple slices and results in a dramatic increase in total scan time. This work utilizes a novel dynamic TSE sequence (cineTSE) to provide analogous information to blood suppression techniques with no increase in scan time over a typical (non-inversion prepared) TSE protocol.