Glossary: Arteriography , Angiography , cerebral angiography, arteriogram. A test to visualize the blood vessels in the head. This is an invasive procedure which requires that a catheter be inserted, usually in the groin or directly into the neck vessels, and threaded into the base of the skull. The dye material is then injected which shows up on x-ray, and rapid succession x-rays are taken to get a picture of the blood vessels in the head as they fill and empty with the dye material. MRI: Magnetic resonance imaging : A technique where a large magnet is used to visualize the contents of the cranium including the brain and blood vessels. This technique is noninvasive with the exception of an intravenous catheter which might be needed to give a contrast agent to better see brain lesions.