The cerebral intravascular enhancement sign is not specific: a contrast-enhanced MRI study

The intravascular enhancement (IVE) sign, also known as the "arterial enhan cement sign", is an abnormal finding in the brain on contrast-enhanced MRI studies. IVE has been described in arterial cerebrovascular disorders. most commonly in acute or subacute arterial ischemic infarcts. However, the spe cificity of this sign has not been established. We describe four patients w ith disorders other than arterial strokes in whom gadolinium-enhanced high- field (1.5 T) MRI suggested IVE. The conditions were herpes simplex viral e ncephalitis, idiopathic cerebellitis, pneumococcal meningitis, and superior sagittal sinus thrombosis with venous infarction. IVE in these cases may b e due to multiple factors, including arterial, venous, perivascular, and le ptomeningeal or sulcal contrast medium accumulation. Our observations sugge st that arterial ischemia, previously described as the cardinal cause df IV E, probably does not explain all instances, and urge caution in interpretin g this sign as a specific MRI manifestation of acute arterial infarction or ischemia.