Evaluation of sampling density on the accuracy of aortic pulse wave velocity from velocity-encoded MRI in patients with Marfan syndrome

Purpose: To evaluate the effect of spatial (ie, number of sampling locations along the aorta) and temporal sampling density on aortic pulse wave velocity (PWV) assessment from velocity-encoded MRI in patients with Marfan syndrome (MFS). Materials and Methods: Twenty-three MFS patients (12 men, mean age 36 ± 14 years) were included. Three PWV-methods were evaluated: 1) reference PWV_i.p. from in-plane velocity-encoded MRI with dense temporal and spatial sampling; 2) conventional PWV_t.p. from through-plane velocity-encoded MRI with dense temporal but sparse spatial sampling at three aortic locations; 3) EPI-accelerated PWV_t.p. with sparse temporal but improved spatial sampling at five aortic locations with acceleration by echo-planar imaging (EPI). Results: Despite inferior temporal resolution, EPI-accelerated PWV_t.p. showed stronger correlation (r = 0.92 vs. r = 0.65, P = 0.03) with reference PWV_i.p. in the total aorta, with less error (8% vs. 16%) and variation (11% vs. 27%) as compared to conventional PWV_t.p.. In the aortic arch, correlation was comparable for both EPI-accelerated and conventional PWV_t.p. with reference PWV_i.p. (r = 0.66 vs. r = 0.67, P = 0.46), albeit 92% scan-time reduction by EPI-acceleration. Conclusion: Improving spatial sampling density by adding two acquisition planes along the aorta results in more accurate PWV assessment, even when temporal resolution decreases. For regional PWV assessment in the aortic arch, EPI-accelerated and conventional PWV assessment are comparably accurate. Scan-time reduction makes EPI-accelerated PWV assessment the preferred method of choice.