False-colour cerebral arteriograph (angiograph) of the skull, showing the branching arteries (normal) which supply oxygenated blood to the brain. Arteriography is the x-ray examination of an artery that has been outlined by the prior injection of a radio-opaque contrast medium. The technique is used to evaluate presence of cerebro- vascular disease, whereby the vessels become blocked by fatty plaques (atheroma) or rupture due to hypertension (high blood pressure), resulting in an inadequate supply of blood (& hence oxygen) to the brain. A sudden & severe attack (a stroke) may lead to paralysis & death.