Interleaved gradient echo planar (IGEPI) and phase contrast CINE-PC flow measurements in the renal artery

ECG-gated phase contrast (CINE-PC) flow measurements in the renal artery help to differentiate between low- and high-grade stenoses. Because conventional CINE-PC acquisitions with high temporal resolution require acquisition times of several minutes, respiratory motion results in a systematic overestimation of renal artery flow. With the use of an interleaved gradient echo-planar technique (IGEPI), total measurement times can be shortened to about 30 seconds, while a high spatial and temporal resolution is maintained. In this study, an IGEPI CINE-PC flow measurement pulse sequence with 16 gradient echoes was compared with a non-breathheld conventional CINE-PC technique. Flow-time curves were measured in volunteers and in patients with suspected renal artery stenosis. With IGEPI CINE-PC, mean flow velocity, vessel cross-sectional area, and mean blood flow were substantially lower by 90% to 25%. Contrast-enhanced 3D MR angiography was used to compare stenosis grading based on flow-time curve patterns with morphologic grading. With IGEPI CINE-PC, all high-grade stenoses (n = 5) were detected, whereas only 66% (n = 3) were found with conventional CINE-PC.