Common and expected postmortem CT observations involving the brain: mimics of antemortem pathology

Postmortem imaging with CT or MR is emerging as an effective technique to augment forensic autopsy. Expected findings on postmortem imaging of the brain may mimic pathologic processes in the living brain, leading to potential misdiagnosis. The purpose of this study is to describe the array of CT findings that can be expected to be present within the brain after death.

A retrospective review was performed using an anonymized data base of 33 postmortem head CTs with no evidence of trauma to the face or scalp. Head CTs were assessed for 1) loss of gray-white differentiation, 2) effacement of the ventricles and cisterns, 3) postmortem intravascular blood distribution, 4) presence of intracranial or intravascular air, and 5) an irregular appearance of the falx. Imaging findings were correlated with autopsy findings.

Visualization of the basal ganglia was noted in 30 (91%) subjects, and the cortical ribbon was appreciated in 14 (42%). The ventricles and cisterns were effaced in 19 (58%) cases. An "expected postmortem blood distribution" was seen in 27 (82%) instances. Intravascular air was present in 14 cases (42%). A "lumpy" falx was present in 20 cases (61%). In 4 cases of subdural or subarachnoid hemorrhage noted on autopsy, but not on CT, retrospective review confirmed that a true discrepancy between the radiology and pathology findings persisted.

Recognition of expected postmortem patterns is required before pathology can be accurately diagnosed. A limitation of CT virtual autopsy is the possibility of missing small blood collections.