Multiphase Segmented K-Space Velocity Mapping in Pulsatile Flow Waveforms |
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| Institution: | 1. Department of Radiology, Helsinki University Central Hospital, Helsinki, Finland;1. Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA;2. Department of Radiology, 3rd Affiliated Hospital, Zhengzhou University, Henan, China;3. Paul C. Lauterbur Research Centre for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China;4. Neuroscience Center and Department of Pediatrics, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA;1. Division of MR Research, Department of Radiology, Johns Hopkins University, Baltimore, MD, USA;2. F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Institute, Baltimore, MD, USA;1. Department of Radiology, University of Pittsburgh, Pittsburgh, PA, United States;2. Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, United States;3. Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, United States;4. Center for Neuroscience Imaging Research, Institute for Basic Science (IBS), Suwon, South Korea;5. Department of Biomedical Engineering, Sungkyunkwan University, Suwon, South Korea;1. UCLA Brain Tumor Imaging Laboratory (BTIL), Center for Computer Vision and Imaging Biomarkers, University of California, Los Angeles, Los Angeles, CA, USA;2. Department of Radiological Sciences, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA;3. Department of Radiology, Juntendo University School of Medicine, Tokyo, Japan;4. Department of Bioengineering, Henry Samueli School of Engineering and Applied Science, University of California Los Angeles, Los Angeles, CA, USA;5. Medical Scientist Training Program, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA;6. Department of Neurosurgery, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA;7. Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA;8. Department of Pathology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA;9. UCLA Neuro-Oncology Program, University of California, Los Angeles, Los Angeles, CA, USA;10. Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA;11. Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA |
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| Abstract: | The aim of the present study was to obtain the precision of flow measurement in breath-hold segmented k-space flow sequences. The results are based on studies of pulsatile flow in a phantom tube. The ultimate purpose is to use these sequences to measure coronary flow. In abdominal and cardiothoracic magnetic resonance imaging the image quality is degraded due to respiratory motion. In the segmented k-space acquisition method, one obtains many phase-encoding steps or views per cardiac phase. This shortens imaging time in the order of phase-encoding lines and makes it possible to image in a single breath-hold, thereby eliminating respiratory artefacts and improving edge detection. With breath-hold multiframe cine flow images it is possible to evaluate flow in all abdominal and cardiothoracic areas, including the coronary arteries. Our study shows that velocity curves shift in time when the number of k-space ky-lines per segment (LPS) are varied; this shift is linear as a function of LPS. The mean velocity Vmean in the center of mass of the pulsatile peak is constant (Vmean = 40.1 ± 2.9 cm/s) and time t = ?10.1 × LPS + 268 (r = 0.993, p < 0.0001). Correlation between theoretical and experimental flow curves is also linear as a function of LPS: C = ?0.977 1 LPS (r = 0.987, p < 0.0001). It is concluded that velocity curves move with LPS and are smoothed when the breath-hold velocity mapping is used. The more LPS is gathered the more inaccurate results are. LPS 7 or more cannot be considered clinically relevant. |
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