Postmortem computed tomography-based evaluation of brain decomposition: Correlation with postmortem interval and cause-of-death determinability

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BACKGROUND: Accurately estimating the postmortem interval (PMI) is essential for forensic investigations. Brain decomposition observed on postmortem computed tomography (PMCT) may provide useful markers to estimate PMI; however, this approach has not been extensively studied. The aim of this study was to classify and quantify brain decomposition using PMCT findings and to investigate its association with PMI, determinability of cause of death, and environmental factors. METHODS: We retrospectively analyzed 176 adult autopsy cases involving preautopsy PMCT. Brain decomposition was classified into five stages using the visual PMCT findings and quantified using brain area-to-length ratios on axial computed tomography slices. Associations between the PMI and determinability of the cause of death were assessed using correlation and regression analyses. RESULTS: Brain decomposition stage and quantitative indices showed strong correlations with PMI (ρ = 0.61 to - 0.69), with high predictive performance for estimating PMI ≥ 7-60 days (area under the curves [AUCs]: 0.904-0.984). Brain area ratio showed the highest accuracy for estimating PMI ≥ 60 days (AUC = 0.984, cutoff ≤ 60.7 %). The rate of undetermined causes of death increased from 7.1 % in stage 0 to 92.9 % in Stage IV. Brain deformation ratio was positively correlated with seasonal effects (p = 0.0017). CONCLUSION: PMCT-based assessment of brain decomposition may provide objective markers for estimating late PMIs and assist in evaluating the likelihood of cause-of-death in decomposed bodies.