NONINVASIVE ANALYSIS OF RENAL-ARTERY BLOOD-FLOW DYNAMICS WITH MR CINEPHASE-CONTRAST FLOW MEASUREMENTS

It was the aim of this study to quantify the measurement of pulsatile flow in the renal artery with the noninvasive magnetic resonance cine phase-contrast (MRCPC) method and combine it with the simultaneous ass essment of pulsatile flow with a transit-time ultrasound (TTUS) flowme ter. In seven foxhounds with a chronically implanted precalibrated TTU S flow probe, MRCPC flow measurements were made in the renal artery wi th a temporal resolution of 32 ms. Mean and pulsatile flow signals wer e compared by the simultaneous ipsi- or contralateral measurement of t he renal blood flow signal by both methods (TTUS and MRCPC). In additi on, comparative MRCPC and TTUS flow measurements were made with artifi cial renal artery stenosis and after the administration of angiotensin II. The mean flow data assessed by the noninvasive MRCPC flow measure ments showed an excellent correlation with the corresponding TTUS reco rdings (r = 0.99). The MRCPC flow signal displayed a waveform of the r enal artery flow profile that was very similar to the TTUS flow pulse. The hemodynamic changes induced by angiotensin II or due to renal art ery stenosis were also reliably detected by MRCPC. MRCPC provides a re liable noninvasive method for the quantification of mean blood flow an d the assessment of the pulsatile flow signal in the renal artery and proves to be sensitive to hemodynamic changes of pathophysiological im portance. Alternatively, the method may be used for studies in physiol ogy that demand a noninvasive approach.