Vascular Malformations of the Brain
On MRI scans (magnetic resonance imaging) these lesions often have a very typical appearance. The malformation shows up as very distinct from the surrounding brain tissue and a radiologist will often be able to see areas of old and recent bleeding nearby. On CT (computed tomography) scans they appear as rounded areas that have a slightly higher density than the rest of the brain. An arteriogram (a test where dye is injected directly into the arteries that supply the brain and x-ray pictures taken) is typically used to diagnose an AVM; cavernous angiomas, however, are rarely seen on arteriograms because the blood flow within them is very slow and only very tiny blood vessels supply the malformation.