Imaging changes of pulmonary thromboembolism on postmortem computed tomography

PMCT findings can vary considerably with the postmortem interval (PMI), potentially complicating the assessment of pulmonary thromboembolism (PTE). Although attenuation changes in antemortem thrombi have been investigated, the postmortem evolution of thrombus imaging characteristics remains insufficiently characterized.

We present the case of a man in his 70s who died of PTE. Serial non-contrast PMCT was performed at 1 h and 96 h postmortem. On the initial scan, the thrombus in the left pulmonary artery measured 45 Hounsfield units (HU), while the adjacent vascular lumen measured 58 HU. On the delayed scan, thrombus attenuation increased to 70 HU, while vascular lumen attenuation decreased to 30 HU. Consequently, the contrast ratio between thrombus and lumen increased from 13% to 40%, thereby enhancing thrombus conspicuity. At autopsy, bilateral pulmonary artery thromboemboli were confirmed.

The progressive enhancement in thrombus conspicuity over time may reflect postmortem physiological processes such as plasma separation and hypostasis, contrasting with the attenuation decline typically described in antemortem thrombi. Despite potential variability of CT acquisition parameters, relative attenuation differences may provide more reliable diagnostic information.

To our knowledge, this is the first report to demonstrate time-dependent imaging evolution of pulmonary thromboemboli using serial non-contrast PMCT. Recognition of such temporal imaging alterations may enhance the diagnostic utility of PMCT and guide the development of time-sensitive postmortem imaging protocols in forensic radiology.