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

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 Meth ods: 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.

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.

IB:LvR provides a surrogate evaluation of AB:LwRs, and may be used as a marker of FGR where autopsy is declined.