Cavernous angiomas are congential vascular hamartomas that are made up of sinusoidal collection of vessels without interspersed normal brain. Blood products of various ages, calcification, and gliosis are also present.
They are occult on angiography and demonstrate increased attenuation on CT. On MR, there is a hemosiderin rim (low signal on all sequences) surrounding areas of methemoglobin. GRE is the most sensitive sequence for the detection of cavernous angiomas.
The patient whose MRI is shown here presented with seizures. CT (not shown) was negative (even in retrospect). MRI showed a right cerebellar hemisphere lesion with a rim that was low on all sequences and had a nidus of increased signal. Post-contrast images (panel D) showed no enhancement. A: T1, B: T2, C: FLAIR, D: Post-contrast, E: GRE, F: DWI.
Simple parenchymal hemorrhages and hemorrhagic tumors may demonstrate similar signal intensity, but parenchymal hemorrhages will appear as slit-like cavities (cavernous angiomas are round) and tumors will not have a complete rim of hemosiderin.
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