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

Abstract

BackgroundPhase 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.PurposeTo 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.Study TypeMethod comparison.Phantom/SubjectsComputer simulation. Seventeen pregnant volunteers.Field Strength/Sequence1.5T and 3T. Cartesian and golden‐angle radial phase contrast MRI.AssessmentThrough 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.Statistical TestsWilcoxon signed‐rank test. Linear regression. Bland–Altman plots. Student's t‐test.ResultsSimulations 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.Data ConclusionSimulations 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.

Cerebral Blood Flow Monitoring in High-Risk Fetal and Neonatal Populations

“…When combined with phase contrast MRI, which quantifies velocity of moving fluids, accurate measurements of fetal blood flow are possible. One major obstacle to this imaging is the necessity of timing image acquisition with the cardiac cycle (47)(48)(49)(50)(51). Cardiac gating is used to time data acquisition with specific phases of the cardiac cycle, and MRI-compatible fetal ECG devices are now available (48,(51)(52)(53)(54)(55).…”

“…One major obstacle to this imaging is the necessity of timing image acquisition with the cardiac cycle (47)(48)(49)(50)(51). Cardiac gating is used to time data acquisition with specific phases of the cardiac cycle, and MRI-compatible fetal ECG devices are now available (48,(51)(52)(53)(54)(55). This technology has now been applied to fetal disease states including IUGR (54) as well as the fetus with cardiac malformations (38).…”

Fetal Cardiovascular MRI – A Systemic Review of the Literature: Challenges, New Technical Developments, and Perspectives

“…1). From then on, the following studies successfully demonstrated the feasibility of MOG for functional PC MRI in healthy and growth-restricted fetuses and fetuses with CHD at both 1.5 and 3 T [22,[47][48][49][50]. PC MRI applying MOG at 3 T revealed better inter-observer agreement, an increased SNR, and better visualization of small pulmonary vessels, compared to 1.5 T [22].…”

“…PC MRI applying MOG at 3 T revealed better inter-observer agreement, an increased SNR, and better visualization of small pulmonary vessels, compared to 1.5 T [22]. Using MOG, flow evaluation of the great fetal vessels was successfully performed revealing the highest image quality for the descending aorta, but also smaller vessel hemodynamics (e. g., of the ductus arteriosus or peripheral pulmonary vessels) were quantified [22,47,50]. Phantom validation studies demonstrated sufficient reliability of MOG [48], and flow results were comparable to experimental studies in fetal lambs [47].…”

“…Phantom validation studies demonstrated sufficient reliability of MOG [48], and flow results were comparable to experimental studies in fetal lambs [47]. In combination with other newly emerging techniques such as motion compensation (see also the following chapters), the accuracy of PC MRI using MOG is continuing to increase, as suggested by current results [50].…”