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Evaluation of ultrafast phase-contrast imaging in the thoracic aorta
J F Debatin1, C P Davis, J Felblinger
1Department of Radiology, Zürich University Hospital, Switzerland.
Purpose:
Two ultrafast phase-contrast (PC) data acquisition strategies, multishot echo-planar imaging (EPI)-PC and segmented k-space fast gradient-echo PC (FASTCARD-PC) were evaluated with regard to their measurement accuracy.
Materials And Method:
Flow measurements of the ascending and descending aorta were acquired in 10 healthy volunteers with an electrocardiogram (ECG)-triggered eight-shot EPI-PC sequence (TR/TE/flip 16/7.4/45 degrees, 32-ms flow-phase interval, 2 x 2 mm in plane resolution), and FASTCARD-PC (six k-lines per band, TR/TE/flip 11/6.1/45 degrees, 132-ms flow-phase interval, 2 x 1 mm in plane resolution). These were compared to flow-volume data acquired with conventional cine-PC (TR/TE/flip 24/7/45 degrees, 48-ms flow-phase interval, 2 x 1 mm in plane resolution). Using cine-PC as a gold standard, the measurement accuracy of FASTCARD-PC and EPI-PC were determined.
Results:
Both EPI-PC and FASTCARD-PC significantly reduced data acquisition times compared to cine PC. EPI-PC flow measurements correlated well with aortic cine-PC flow-volume determinations (r = 0.98). Reflecting poorer temporal resolution, FASTCARD-PC measurements were less accurate (p < 0.05), evidenced by poor correlation with cine-PC data (r = 0.62).
Conclusion:
Ultrafast PC measurements are possible. In contrast to the segmented k-space PC technique, which is limited in temporal resolution, multishot EPI-PC provides high measurement accuracy in pulsatile vessles while keeping the image acquisition interval short enough for a comfortable breath-hold.