Well circumscribed heterogeneous lesion in the posterior pons, superior cerebellar peduncle with following signal characteristics:
T1: heterogeneous high signal with surrounding ring of slightly hypointensity.
T2: High signal intensity with markedly hypointense ring surrounding.
Gradient Echo Images: Lesion "blooms" increasing in size with marked region of hypointensity.
No significant enhancement (minimal linear enhancement anteriorly of a draining vein).

Cavernous angiomas are "lobulated mulberry-like" collections of endothelial lined vascular channels which may contain calcifications. Incidence of approximately 0.5% on cranial MR's. 77% are supratentorial with 23% infratentorial. Spinal cord may be involved.

May present with seizure (40-70%), focal neuro deficits (35-50%) or headache (25-30%). Some hemorrhage is present in almost every cavernous angioma, but "catastrophic hemorrhage" is distinctly uncommon." Risk of symptomatic hemorrhage ranged from 0.1% to 1.3% in studies. Prior bleed increases the risk of another significant bleed (approximately 25% risk).

On CT, CA's are heterogeneous and mottled and iso to hyperdense to brain. They may contain calcium. If they bleed, they are difficult to discern from hemorrhagic metastasis.

MR: Appearance reflects blood products of various ages. Acute blood (deoxyhemoglobin) is isointense to brain. Subacute blood - hyperintense. Old hemorrhage (hemosiderin) is hypointense. On T2 images, old hemodiderin is markedly hypointense. A thin rim of hemosiderin surrounds which is slightly hypointense on T1 and markedly hypointense on T2. "Blooming effect" is seen on gradient echo sequences. Gradient echo can also help find additional lesions. Most CA's are not seen on angiography.