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KMID : 0386119960340060729
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Journal of the Korean Radiological Society
1996 Volume.34 No. 6 p.729 ~ p.735
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Velocity Window for Detection of Flow with MR Phase Imaging
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Lim Tae-Hwan
Nuno J. Tavares
Nola M. Hylton
Charles B. Higgines
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Abstract
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Purpose : To prepare a data base for semi-quantitative measurement of blood flow velocity on MR phase imagingtechnique by analyzing the characteristics of flow image according to the ranges of flow velocity. Materials and
Methods : We obtained MR phase images of flow with velocity ranging from 0 to 70cm/sec. A straight flow tube with2.09cm internal diameter and a flow tube with 75% stenosis were used as flow phantoms for this study. MR imagings were performed on a 0.35 T MR imaging system.
Results : At a velocity of 0-3cm/sec, the MR phase signal proceeded from an equivocal phase change to a homogeneous intraluminal signal intensity. Ata flow velocity of 3.1cm/sec,first phase wrap occurred, and there were two phase wraps up to 15cm/sec of flow velocity. In this velocity range, the MR phase image revealed an isocentric circular target appearance. At a velocity range of 15-30cm/sec, three to four phase wraps occurred, and the MR phase image showed a multiple target appearance. At a velocity above30cm/sec, the MR phase image showed an irregular unstructured appearance and above 50cm/sec, there were no flow signals and only noise-like signals were observed. The flow phantom of the stenosis model demonstrated the same phase image pattern as the high velocity flow in the stenotic and post-stenotic areas. In the pre-stenotic area, acharacteristic reversed laminar flow profile was observed. Conclusion : Flow velocity can be detected semiquantitatively as velocity ranges on MR phase imaging. The results of the experiment using a stenotic model suggest that MR phase imaging can be used as a modality for investigation of flow velocity and profiles.
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KEYWORD
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Magnetic resonance(MR), vascular studies
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