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 Kooi^2
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.

Xihai Zhao¹, Niranjan Balu², Wenbo Liu², Jinnan Wang³, Huilin Zhao⁴, Jianrong Xu⁴, and Chun Yuan^1,2
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.

Niranjan Balu¹, Vasily Yarnykh¹, William Kerwin¹, Jinnan Wang², and Chun Yuan^1
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.

General Leung^1,2, Helen Cheung², Stephanie E Chiu¹, Betty Wong³, David Cole³, and Alan R Moody^1,2
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.

Andrew David Scott^1,2, Jennifer Keegan^1,2, and David Firmin^1,2
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.

Gregory John Metzger¹, Lance Delabarre¹, Xiaoming Bi², Saurabh Shah², Sven Zuehlsdorff², Tommy Vaughan¹, Kamil Ugurbil¹, and Pierre-Francois van de Moortele^1
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.

Peter Koken¹, Holger Eggers¹, Gabrielle Beck², and Peter Börnert^1
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.

Markus Henningsson¹, Christian Stehning², Claudia Prieto¹, Peter Koken², and Rene M Botnar^1
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.

Mehdi Hedjazi Moghari¹, Tamer Basha¹, Mehmet Akçakaya¹, Alan O’Connor¹, Lois Goepfert¹, Kraig V Kissinger¹, Beth Goddu¹, Doug Stanton², Warren J Manning¹, and Reza Nezafat^1
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.