ASSESSMENT OF FLOW IN THE RIGHT HUMAN CORONARY-ARTERY BY MAGNETIC-RESONANCE PHASE-CONTRAST VELOCITY-MEASUREMENT - EFFECTS OF CARDIAC AND RESPIRATORY MOTION

Flow in the human right coronary artery was determined using magnetic resonance phase contrast velocity quantification. Two methods were app lied to reduce respiratory motion: imaging during breath holding, whic h is fast, and retrospective respiratory gating, which has a high temp oral resolution (32 ms) in the cardiac cycle. Vessel cross-sectional a rea, through-plane velocity, and volume flow were determined in six he althy subjects. In-plane vessel displacement during the cardiac cycle, caused by cardiac contraction, was about 2-4 mm within a time frame o f 32 ms in systole and early diastole. The motion resulted in blurring of images obtained during breath holding caused by the large acquisit ion time window (126 ms) within the cardiac cycle. Therefore, only wit h a high temporal resolution correct velocity images over the entire c ardiac cycle could be obtained. The time- and cross-sectionally averag ed velocity was 7 +/- 2 cm/s, and the volume flow was 30 +/- 10 ml/min .