PURPOSE
To compare pulse wave velocity (PWV) measurements obtained from radially undersampled 4D phase-contrast MRI (PC-MRI) with 2DPC measurements and to evaluate four PWV algorithms.
MATERIALS AND METHODS
PWV was computed from radially undersampled 3-dimensional, 3-directionally velocity-encoded PC-MRI acquisitions performed on a 3T MR scanner in 18 volunteers. High temporal resolution 2DPC scans serving as a reference standard were available in 14 volunteers. Four PWV algorithms were tested: time-to-upstroke (TTU), time-to-peak (TTP), time-to-foot (TTF), and cross-correlation (XCorr). Bland-Altman analysis was used to determine inter- and intraobserver reproducibility and to compare differences between algorithms. Differences in age and PWV measurements were analyzed with Student’s t-tests. The variability of age-corrected data was assessed with a Brown-Forsythe ANOVA test.
RESULTS
2D (4.6–5.3m/s) and 4D (3.8–4.8m/s) PWV results were in agreement with previously reported values in healthy subjects. Of the four PWV algorithms, the TTU, TTF, and XCorr algorithms gave similar and reliable results. Average biases of +0.30m/s and −0.01m/s were determined for intra- and interobserver variability, respectively. The Brown-Forsythe test revealed that no differences in variability could be found between 2D and 4D PWV measurements.
CONCLUSION
4D PC-MRI with radial undersampling provides reliable and reproducible measurements of PWV. TTU, TTF, and XCorr were the preferred PWV algorithms.
Eighteen human subjects underwent echo-planar magnetic resonance (MR) imaging of the whole body at 1.5 T. A stack of axial images was obtained from the top of the head to the feet with gradient-echo, spin-echo, and inversion-recovery spin-echo pulse sequences by moving the patient table through the magnet isocenter. In all examinations, the subjects tolerated the procedure well and table motion was uniform. Image quality depended on careful setting of the transmit frequency, gain, and shims. Results were easily obtained and reproducible in all cases in as little as 18 seconds.
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