3D mapping of the placenta during early gestation using free‐breathing multiecho stack‐of‐radial MRI at 3T

Abstract

Multiecho gradient-echo Cartesian MRI characterizes placental oxygenation by quantifying . Previous research was performed at 1.5T using breath-held 2D imaging during later gestational age (GA). To evaluate the accuracy and repeatability of a free-breathing (FB) 3D multiecho gradient-echo stack-of-radial technique (radial) for placental mapping at 3T and report placental during early GA. Prospective. Thirty subjects with normal pregnancies and three subjects with ischemic placental disease (IPD) were scanned twice: between 14-18 and 19-23 weeks GA. 3T. FB radial. Linear correlation (concordance coefficient, ρc ) and Bland-Altman analyses (mean difference, MD) were performed to evaluate radial mapping accuracy compared to Cartesian in a phantom. Radial mapping repeatability was characterized using the coefficient of repeatability (CR) between back-to-back scans. The mean and spatial coefficient of variation (CV) of was determined for all subjects, and separately for anterior and posterior placentas, at each GA range. ρc was tested for significance. Differences in mean and CV were tested using Wilcoxon Signed-Rank and Rank-Sum tests. P < 0.05 was considered significant. Z-scores for the IPD subjects were determined. FB radial demonstrated accurate (ρc ≥0.996; P < 0.001; |MD|<0.2s-1 ) and repeatable (CR<4s-1 ) mapping in a phantom, and repeatable (CR≤4.6s-1 ) mapping in normal subjects. At 3T, placental mean ± standard deviation was 12.9s-1 ± 2.7s-1 for 14-18 and 13.2s-1 ± 1.9s-1 for 19-23 weeks GA. The CV was significantly greater (P = 0.043) at 14-18 (0.63 ± 0.12) than 19-23 (0.58 ± 0.13) weeks GA. At 19-23 weeks, the CV was significantly lower (P < 0.001) for anterior (0.49 ± 0.08) than posterior (0.67 ± 0.11) placentas. One IPD subject had a lower mean than normal subjects at both GA ranges (Z<-2). FB radial provides accurate and repeatable 3D mapping for the entire placenta at 3T during early GA. 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:291-303.