Pseudo-Subarachnoid Hemorrhage: A Potential Imaging Pitfall Associated with Diffuse Cerebral Edema

diffuse cerebral edema and increased attenuation in the basilar cisterns resembling subarachnoid hemorrhage. On the basis of autopsy (three cases) and lumbar puncture (four cases) findings, true subarachnoid hemorrhage was reasonably excluded. Pathophysiologic changes that occur with diffuse cerebral edema are explored, with proposed explanations for the appearance of a pseudo-subarachnoid hemorrhage. Increased attenuation of the basal cisterns and sub-arachnoid spaces on CT scans is a characteristic find-ing of acute subarachnoid hemorrhage (SAH). Sev-eral radiographic mimics of SAH have been reported, including pyogenic leptomeningitis, CT appearance of intrathecally administered contrast material, and leakage of high-dose intravenous contrast mediu