Imaging changes of pulmonary thromboembolism on postmortem computed tomography: a time-dependent observation

Postmortem CT (PMCT) findings can change over time, which may affect the assessment of pulmonary thromboembolism (PTE). While attenuation characteristics of antemortem thrombi have been studied, time-dependent imaging evolution after death remains unclear. We examined serial non-contrast PMCT images in a man in his seventies who died of PTE. Scans were obtained 1 hour and 96 hours after death and correlated with autopsy findings. Initially, the pulmonary artery thrombus showed slightly lower attenuation than the surrounding blood (45 HU vs 58 HU). At 96 hours, thrombus density increased (70 HU) while luminal attenuation decreased (30 HU), enhancing thrombus conspicuity. Bilateral pulmonary emboli were confirmed at autopsy. This case demonstrates time-dependent imaging changes of pulmonary thromboemboli on serial PMCT. Increasing thrombus contrast over time likely reflects postmortem plasma separation and hypostasis. Recognition of such changes may improve interpretation of PMCT findings and support more reliable diagnosis of PTE in forensic imaging.