Many things. To look at the blood vessels in the brain. You will have some discomfort at the site where there needle and tube are placed into the artery in the groin you may feel warmth in your face, get a metallic taste in your mouth, see flashing lights and/or feel dizzy for brief periods, 8-10 seconds, when the x-ray dye is injected.
Vascular anatomy. Angiograms are the gold standard for defining the vascular anatomy of the brain, but i can't tell you why you need one. They will demonstrate intracranial atherosclerosis, aneurysms, feeding and draining vessels to an arteriovenous malformation, vascular feeding vessels to a tumor, vascular steal phenomemon and many other processes. When the dye is injected, you may get a warm sensation.
Blood vessel . Of the brain evaluation. Check out radiologyinfo.Org.