Postmortem Magnetic Resonance Imaging of In Utero Fetuses and Its Relationship With Postmortem Interval: A Multi-Organ Observational Study on Reduced Fetuses of Complicated Multiple Pregnancies

Background: Despite technological advancements in perinatal imaging, autopsy examination is still regarded as the reference standard to determine the time and reason of the fetal death.

Purpose: This study was conducted to identify the intrauterine postmortem magnetic resonance imaging (PMMR) findings of fetuses, who underwent radiofrequency ablation (RFA).

Study type: Prospective.

Population: Fifty-three twin/triplet complicated pregnancies scheduled for selective reduction of one of the fetuses by RFA were included.

Field strength/sequence: The imaging methods used are T1-weighted gradient-echo imaging (T1 GRE), T2 half-Fourier acquisition single-shot turbo spin-echo (SSTSE), and diffusion-weighted imaging (DWI) sequences.

Assessment: The MRIs were interpreted by three radiologists.

Statistical tests: Data were analyzed using the software package SPSS Statistics Version 22.0. The used tests included one-way analysis of variance (ANOVA) and Duncan tests (significance level: P value <0.05). This analysis was performed with scikit-learn library (version 1.1.1) in Python version 3.9.

Results: Average PMMR scores of orbit, brain, and abdomen showed significant differences among different PM interval subgroups. The brain apparent diffusion coefficient (ADC) numbers of reduced and living fetuses were significantly different at any PM interval. To determine which findings are closely associated with the timing of fetal death, five different methods of feature selection were employed. The top eight selected features achieved the highest area under the curve (AUC) of 78.19%.

Data conclusion: In utero, PMMR findings may be associated with the time of fetal death. Among different fetal organs evaluated, particularly PMMR top eight features specifically scores of orbits were associated with PM intrauterine time after death.