Fetal Flow Quantification in Great Vessels Using Motion-Corrected Radial Phase Contrast MRI: Comparison With Cartesian.

Abstract

Phase contrast MRI in the great vessels is a potential clinical tool for managing fetal pathologies. One challenge is the uncontrollable fetal motion, potentially corrupting flow quantifications. To demonstrate improvements in fetal blood flow quantification in great vessels using retrospectively motion-corrected golden-angle radial phase contrast MRI relative to Cartesian phase contrast MRI. Method comparison. Computer simulation. Seventeen pregnant volunteers. 1.5T and 3T. Cartesian and golden-angle radial phase contrast MRI. Through computer simulations, radial (with and without retrospective motion correction) and Cartesian phase contrast MRI were compared using flow deviations. in vivo Cartesian and radial phase contrast MRI measurements and reconstruction qualities were compared in pregnancies. Cartesian data were reconstructed into gated reconstructions (CINEs) after cardiac gating with metric optimized gating (MOG). For radial data, real-time reconstructions were performed for motion correction and MOG followed by CINE reconstructions. Wilcoxon signed-rank test. Linear regression. Bland-Altman plots. Student's t-test. Simulations showed significant improvements (P < 0.05) in flow accuracy and reconstruction quality with motion correction ([mean/peak] flow errors with ±5 mm motion corruption: Cartesian [35 ± 1/115 ± 7] mL/s, motion uncorrected radial [25 ± 1/75 ± 2] mL/s and motion-corrected radial [1.0 ± 0.5/-5 ± 1] mL/s). in vivo Cartesian reconstructions without motion correction had lower quality than the motion-corrected radial reconstructions (P < 0.05). Across all fetal mean flow measurements, the bias [limits of agreement] between the two measurements were -0.2 [-76, 75] mL/min/kg, while the linear regression coefficients were (Mradial = 0.81 × MCartesian + 29.8 [mL/min/kg], r2 = 0.67). The corresponding measures for the peak fetal flows were -23 [-214, 167] mL/min/kg and (Pradial = 0.95 × PCartesian -1.2 [mL/min/kg], r2 = 0.80). Cartesian reconstructions of low quality showed significantly higher estimated mean and peak (P < 0.05) flows than the corresponding radial reconstructions. Simulations showed that radial phase contrast MRI with motion compensation improved flow accuracy. For fetal measurements, motion-corrected radial reconstructions showed better image quality than, and different flow values from, Cartesian reconstructions. Level of Evidence 1. Technical Efficacy Stage 1. J. MAGN. RESON. IMAGING 2021;53:540-551.