Feasibility of Postmortem Imaging Assessment of Brain: Liver Volume Ratios with Pathological Validation

Introduction Organ volumes at postmortem magnetic resonance imaging (PMMR) should reflect autopsy organ weights, and thus brain: liver volume ratios on imaging could be a surrogate for weight volume ratios at autopsy to indicate fetal growth restriction (FGR). This study aims to determine whether imaging-based organ volume ratios can replace autopsy organ weight ratios. Materials and Methods An unselected cohort of perinatal deaths underwent PMMR prior to autopsy. Semiautomated brain and liver volumes were compared to autopsy organ weights and ratios. Ratios were compared using Bland-Altman plots, and intra- and interobserver variability was assessed. Results A total 49 fetuses (25 male, 51%) at 17–42 weeks gestation were ­assessed. There was a reasonable correlation between autopsy-derived brain: liver weight ratios (AB: LwR) and imaging-derived brain: liver volume ratios (IB: LvR; r = 0.8). The mean difference between AB: LwR and IB: LvR was +0.7 (95% limits of agreement range −1.5 to +2.9). In a small subset where FGR was present, the optimal IB: LvR ≥5.5 gave 83.3% sensitivity and 86.0% specificity for diagnosis. There was acceptable agreement within readers (mean difference in IB: LvRs 0.77 ± 2.21) and between readers −0.36 ± 0.68. Conclusion IB: LvR provides a surrogate evaluation of AB: LwRs, and may be used as a marker of FGR where autopsy is declined.