Racking the brain: Detection of cerebral edema on postmortem computed tomography compared with forensic autopsy

• Postmortem swelling of the brain is a typical finding on PMCT and occurs concomitant with potential antemortem or agonal brain edema.
• Cerebral edema despite normal postmortem swelling is indicated by narrowed temporal horns and symmetrical herniation of the cerebral tonsils on PMCT.
• Cases with intoxication or asphyxia demonstrated higher deviations of the attenuation between white and gray matter (>20 Hounsfield Units) and a ratio >1.58 between the gray and white matter.
• The Hounsfield measurements of the white and gray matter help to determine the cause of death in cases of intoxication or asphyxia.

PurposeThe purpose of this study was to compare postmortem computed tomography with forensic autopsy regarding their diagnostic reliability of differentiating between pre-existing cerebral edema and physiological postmortem brain swelling.Materials and methodsThe study collective included a total of 109 cases (n = 109/200, 83 male, 26 female, mean age: 53.2 years) and were retrospectively evaluated for the following parameters (as related to the distinct age groups and causes of death): tonsillar herniation, the width of the outer and inner cerebrospinal fluid spaces and the radiodensity measurements (in Hounsfield Units) of the gray and white matter.The results were compared with the findings of subsequent autopsies as the gold standard for diagnosing cerebral edema. p-Values <0.05 were considered statistically significant.ResultsCerebellar edema (despite normal postmortem swelling) can be reliably assessed using postmortem computed tomography and is indicated by narrowed temporal horns and symmetrical herniation of the cerebellar tonsils (p < 0.001). There was a significant difference (p < 0.001) between intoxication (or asphyxia) and all other causes of death; the former causes demonstrated higher deviations of the attenuation between white and gray matter (>20 Hounsfield Units), and the gray to white matter ratio was >1.58 when leukoencephalopathy was excluded.ConclusionsDespite normal postmortem changes, generalized brain edema can be differentiated on postmortem computed tomography, and white and gray matter Hounsfield measurements help to determine the cause of death in cases of intoxication or asphyxia. Racking the brain about feasible applications for a precise and reliable brain diagnostic forensic radiology method has just begun.

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