by Anne G. Osborn, MD, FACR and Miral D. Jhaveri, MD, MBA
Autopsied case of acute necrotizing encephalopathy (ANE) shows bilateral hemorrhagic necrosis in the medial thalami. (Courtesy R. Hewlett, MD).
Virus-associated ANE in an obtunded 5-year-old girl shows bilateral medial thalamic hyperintensities on T2WI. T2* GRE shows hemorrhagic foci. DWI shows restricted diffusion in the lesions. In this case, the etiology was influenza A, but the pathology is identical to ANE caused by SARS-CoV-2.
Coronal autopsied case of acute hemorrhagic leukoencephalopathy (AHLE) shows innumerable petechial hemorrhages in the subcortical and deep white matter (WM) extending into the subcortical U-fibers. Note striking sparing of the cortex and basal ganglia. Findings are identical in critical illness-associated cerebral microbleeds.
Axial T2* SWI in a case of viral infection and acute clinical deterioration show multiple tiny WM microbleeds. AHLE was confirmed by biopsy.
Gross autopsy shows 2 areas of gross hemorrhagic necrosis in the left hemispheric WM. Findings and clinical history of prior flu-like illness with a rapidly progressive clinical course are characteristic of a viral exanthem with AHLE. (Courtesy R. Hewlett, MD.)
Axial T2* GRE in a patient with rapid decline after a flu-like viral illness shows a large left frontal hemorrhage with numerous blooming foci in multiple subcortical WM lesions. This is AHLE. (Courtesy R. Ramakantan, MD).
Axial FLAIR MR in a 32-year-old man with COVID-19 on intubation who developed altered mental status shows symmetric hyperintensity in the globi pallidi.
Axial DWI in the same patient shows mild restricted diffusion in the outer margins of both globi pallidi. Hypoxic-ischemic encephalopathy (HIE) is common in patients with severe COVID-19, and the globus pallidi are commonly affected.
Axial NECT scan in a 42-year-old man with COVID-19 was obtained shortly before the patient expired. Severe cerebral edema is present, seen here as diffuse low-density brain with effacement of all basilar cisterns. Both hemispheres and the cerebellum are affected.
More cephalad NECT shows the gray matter-WM interfaces are completely effaced. The lateral ventricles are small, and the surface sulci are obliterated. The patient was pronounced brain dead shortly after the scan was obtained.
Axial FLAIR in a 47-year-old woman with COVID-19 and altered mental status shows bilateral, nearly symmetric patchy perirolandic hyperintensities.
Axial DWI in the same patient shows restricted diffusion in the perirolandic areas of both hemispheres, mild HIE.
