Vessel Wall Imaging & Coronary MRA
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Monday May 9th
Room 511A-C  16:30 - 18:30 Moderators: Marianne E. Kooi and Kuncheng Li

16:30 110.   Carotid plaque characteristics at MRI and recurrent clinical cerebrovascular ischemic events:  
Robert Kwee1, Robert van Oostenbrugge2, Werner Mess2, Rob van der Geest3, Johannes ter Berg4, Cees Franke5, Arthur Korten6, Bé Meems7, Jos van Engelshoven2, Joachim Wildberger2, and Eline Kooi2
1Maastricht University Medical Center, Maastricht, Limburg, Netherlands, 2Maastricht University Medical Center, Netherlands, 3Leiden University Medical Center, 4Orbis Medical Center Sittard, Netherlands, 5Atrium Medical Center Parkstad Heerlen, Netherlands, 6Laurentius Hospital Roermond, Netherlands, 7VieCuri Medical Center Venlo, Netherlands

The results of this first study from mainland Europe suggest that the presence of intraplaque hemorrhage, larger lipid-rich necrotic core volume, and larger maximum vessel wall thickness of carotid plaques are associated with the recurrence of clinical cerebrovascular ischemic events. It confirms previous studies that intraplaque hemorrhage may predict future TIA or stroke. Assessment of carotid plaque characteristics by MRI may help improving patient selection for carotid endarterectomy.

16:42 111.   WITHDRAWN
16:54 112.   Characterization of Carotid Atherosclerotic Plaque Compositions by Single Magnetic Resonance Imaging Sequence: A Comparison Study with Multicontrast Plaque Imaging at 3T  -permission withheld
Xihai Zhao1, Niranjan Balu2, Wenbo Liu2, Jinnan Wang3, Huilin Zhao4, Jianrong Xu4, and Chun Yuan1,2
1Department of Biomedical Engineering & Center for Biomedical Imaging Research, School of Medicine, Tsinghua University, Beijing, China, People's Republic of,2Department of Radiology, University of Washington, Seattle, WA, United States, 3Philips Research North America, Briarcliff Manor, NY, United States, 4Department of Radiology, Renji hospital, Shanghai Jiao Tong University, Shanghai, China, People's Republic of

Multicontrast vessel wall imaging has been widely used for characterizing carotid atherosclerosis. However, the long scan times associated with acquisition of several contrast weightings may limit clinical application. Recent 3D black-blood MRI techniques with large-coverage and short-scan-time can potentially be used to assess carotid morphology and plaque composition. Using a single sequence for fast assessment of plaque characteristics is therefore desirable in screening for high-risk population. In this study, we compare plaque assessment using a 3D isotropic sequence (3D-MERGE) with multicontrast imaging protocol. We find that 3D-MERGE is a promising non-invasive technique for screening arterial plaque burden and lipid-rich plaques.

17:06 113.   Interpretation of tissue contrast in a rapid black-blood gradient echo sequence with motion-sensitized driven equilibrium (MSDE) preparation (3D MERGE) for 3D isotropic high-resolution imaging of the vessel wall and its application for hemorrhage detection 
Niranjan Balu1, Vasily Yarnykh1, William Kerwin1, Jinnan Wang2, and Chun Yuan1
1Radiology, University of Washington, Seattle, Washington, United States, 2Philips Research North America, Seattle, Washington, United States

A new 3D black-blood sequence, 3D-MERGE, has been recently proposed for fast isotropic high-resolution plaque imaging of the vessel wall and validated for the assessment of plaque morphology. However, contrast properties of this 3D technique have not been established limiting its application in studies of plaque composition. 3D-MERGE combines motion-sensitized driven equilibrium (MSDE) preparation with non-steady-state FLASH-type readout, which makes interpretation and management of tissue contrast for this technique a rather complex problem. In this study, we characterize contrast properties of 3D-MERGE and demonstrate its usefulness for in vivo identification of intraplaque hemorrhage.

17:18 114.   Haptoglobin Phenotype Modulates MRIPH Signal 
General Leung1,2, Helen Cheung2, Stephanie E Chiu1, Betty Wong3, David Cole3, and Alan R Moody1,2
1Medical Biophysics, University of Toronto, Toronto, Ontario, Canada, 2Medical Imaging, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada, 3Division of Biochemistry & Genetics, Sunnybrook Health Sciences Centre

Intraplaque Haemorrhage (IPH) has been shown to be a predictor of patient outcome. Haptoglobin, a haemoglobin binding protein, appears to modulate the MR signal in vitro. In-vivo, haptoglobin phenotypes appears to be associated with MRIPH status.

17:30 115.   High resolution 3D coronary vessel wall imaging with near 100% respiratory efficiency using epicardial fat tracking: Reproducibility and comparison with standard methods 
Andrew David Scott1,2, Jennifer Keegan1,2, and David Firmin1,2
1Cardiovascular Magnetic Resonance Unit, Imperial College London, London, United Kingdom, 2Cardiovascular Magnetic Resonance Unit, The Royal Brompton and Harefield NHS Foundation Trust, London, United Kingdom

Coronary wall measurements must be reproducible for longitudinal studies. Navigator-gated 2D TSE and spiral techniques are commonly used, although respiratory efficiency is low and variable. Beat-to-beat respiratory motion correction (B2B-RMC) can correct for tidal respiratory motion with ~100% respiratory efficiency, allowing 3D vessel coverage in a reasonable duration. We compared vessel wall thicknesses using B2B-RMC 3D spiral with navigator-gated 2D TSE and 2D spiral imaging and assessed intra-observer, inter-observer and inter-study reproducibility. Reproducibility was excellent with B2B-RMC and good with navigator-gated techniques. B2B-RMC enables reproducible 3D coronary wall assessment within reasonable durations which will permit improved assessment of atherosclerotic disease.

17:42 116.   Left Coronary Artery Imaging at 7T: Initial Results using Multiple B1+ Shimming Algorithms and Targets 
Gregory John Metzger1, Lance Delabarre1, Xiaoming Bi2, Saurabh Shah2, Sven Zuehlsdorff2, Tommy Vaughan1, Kamil Ugurbil1, and Pierre-Francois van de Moortele1
1Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, United States, 2Siemens Healthcare, Cardiovascular MR R&D, Chicago, IL, United States

Imaging of the left coronary artery was achieved with high contrast at 7T. The challenges of low peak B1+ and poor transmit homogeneity were overcome by RF pulse and region specific B1+ shimming strategies making us of a 16-channel transceiver TEM stripline array driven by 16, 1 kW amplifiers with independent phase and gain control.

17:54 117.   Water/Fat resolved Whole-Heart Imaging for Coronary MRA  -permission withheld
Peter Koken1, Holger Eggers1, Gabrielle Beck2, and Peter Börnert1
1Philips Research Laboratories, Hamburg, Germany, 2Philips Healthcare, Best, Netherlands

Fat suppression is essential to improve contrast in coronary MR-angiography (CMRA) but fat also contains diagnostic information. Therefore, in this work whole heart CMRA imaging is proposed that delivers both, the coronary tree and the fat signal distribution at the same spatial resolution without extra scan time. We propose a gradient multi-echo sequence for whole heart CMRA which acquires two or three echoes at both polarities of an alternating readout gradient, allowing an iterative Dixon water/fat separation. This concept was applied and validated in volunteers. Two different magnetization preparation techniques and their influence on the fat signal were investigated.

18:06 118.   Whole-heart coronary MRA using 2D self-navigation 
Markus Henningsson1, Christian Stehning2, Claudia Prieto1, Peter Koken2, and Rene M Botnar1
1Division of Imaging Sciences & Biomedical Engineering, King's College London, London, United Kingdom, 2Philips Research Europe, Hamburg, Germany

Self-navigation techniques have been proposed to improve respiratory motion compensation in CMRA. However static structures within the navigator image can impede self-navigation motion estimation. To overcome this problem we have implemented a 2D Self-navigator by adding phase encoding gradients to the dummy pulses in a bSSFP sequence. With this approach we calculated foot-head and anterior-posterior motion and performed retrospective translational motion correction. We compared this novel method with a “traditional” 1D self-navigator, and a diaphragmatic 1D pencil beam navigator with a tracking factor 0.6. Initial results show improved motion correction with the 2D self-navigator.

18:18 119.   A Joint Prospective-Retrospective Respiratory Navigator for Contrast Enhanced Whole-Heart Coronary MRI 
Mehdi Hedjazi Moghari1, Tamer Basha1, Mehmet Akçakaya1, Alan O’Connor1, Lois Goepfert1, Kraig V Kissinger1, Beth Goddu1, Doug Stanton2, Warren J Manning1, and Reza Nezafat1
1Dept. of Medicine (Cardiovascular Div.), Beth Israel Deaconess Medical Center, Harvard Medical Sch., Boston, MA, United States, 2Philips Research

We have evaluated a joint prospective-retrospective respiratory motion compensation technique for coronary MRI. Studies in respiratory motion phantom and in vivo experiments were used to validate the proposed method.