The most frequent diagnoses made at brain MR imaging in patients with COVID-19 are acute and subacute infarcts. Other common findings included a constellation of leukoencephalopathy and microhemorrhages, leptomeningeal contrast enhancement, and cortical FLAIR signal abnormality.
Meningitis and encephalitis are uncommon in patients with COVID-19 and
neurologic symptom. Also cortical FLAIR hyperintensity should be secondary to encephalitis. Nonspecific cortical pattern of T2 FLAIR hyperintense signal with associated restriction diffusion that may be caused by systemic toxemia, viremia and-or hypoxic effects.
Cortical FLAIR signal abnormality has a broad differential diagnosis and can include encephalitis, postictal state, PRES, as well as acute ischemia.
