Abstract.
The aim of this study was to evaluate a velocity-encoded cine-MR (VEC-MR) sequence in measuring flow velocities up to two times the velocity encoding value (VENC) in a flow phantom and to validate the method for assessing poststenotic jet velocities in postoperative patients after aortic coarctation. In vitro, a flow phantom was used (0.5T; TR/TE: 51/8 ms, flip angle=30°, FOV=280 mm, 128×256 matrix VENC 40 or 80 cm/s). On binary images, maximum flow velocities (Vmax) were calculated with a region of interest (ROI, 8 pixels). With aliasing, Vmax was calculated by VENC+(Valiasing). In vivo, 16 postoperative patients after aortic coarctation underwent double-oblique VEC-MR imaging through the aortic arch (ECG triggering, 16 phases/RR, TR=600–800 ms, flow-encoding cranio-caudal, VENC=2 m/s). Peak systolic velocities were measured and transthoracic Doppler echocardiography (TTDE) was performed. In vitro, there were excellent correlations for MR velocity measurements with and without aliasing (r=0.99) and for true and MR-derived flow velocities (r=0.99). In vivo, there was good correlation between VEC-MR and TTDE-assessed Vmax values in the aorta at the former coarctation site (r=0.90, n=16). Aliasing occurred in 13 patients. VEC-MR is a useful modality for assessing jet velocities in the follow-up of patients after aortic coarctation. Despite of aliasing, accurate velocity measurements up to two times VENC are possible using binary images.
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Henk, C.B., Grampp, S., Koller, J. et al. Elimination of errors caused by first-order aliasing in velocity encoded cine-MR measurements of postoperative jets after aortic coarctation: in vitro and in vivo validation. Eur Radiol 12, 1523–1531 (2002). https://doi.org/10.1007/s00330-001-1176-2
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DOI: https://doi.org/10.1007/s00330-001-1176-2