Cerebral angiography is a form of angiography which provides images of blood vessels in and around the brain, thereby allowing detection of abnormalities such as arteriovenous malformations and aneurysms. It was pioneered in 1927 by the Portuguese neurologist Egas Moniz at the University of Lisbon, who also helped develop thorotrast for use in the procedure. Typically a catheter is inserted into a large artery and threaded through the circulatory system to the carotid artery, where a contrast agent is injected. A series of radiographs are taken as the contrast agent spreads through the brain's arterial system, then a second series as it reaches the venous system. Prior to the 1970s the typical technique involved a needle puncture directly into the carotid artery, as depicted in the 1973 horror filmThe Exorcist, which was replaced by the current method of threading a catheter from a distant artery due to common complications caused by trauma to the artery at the puncture site in the neck. For some applications cerebral angiography may yield better images than less invasive methods such as computed tomography angiography and magnetic resonance angiography. In addition, cerebral angiography allows certain treatments to be performed immediately, based on its findings. In recent decades, cerebral angiography has so assumed a therapeutic connotation thanks to the elaboration of endovascular therapeutic techniques. Embolization over time has played an increasingly significant role in the multimodal treatment of cerebral MAVs, facilitating subsequent microsurgical or radiosurgical treatment. Another type of treatment possible by angiography is the introduction of metal coils through the catheter already in place and maneuvered to the site of aneurysm; over time these coils encourage formation of connective tissue at the site, strengthening the vessel walls. In some jurisdictions, cerebral angiography is required to confirm brain death. Prior to the advent of modern neuroimaging techniques such as MRI and CT in the mid-1970s, cerebral angiographies were frequently employed as a tool to infer the existence and location of certain kinds of lesions and hematomas by looking for secondary vascular displacement caused by the mass effect related to these medical conditions. This use of angiography as an indirect assessment tool is nowadays obsolete as modern non-invasive diagnostic methods are available to image many kinds of primary intracranial abnormalities directly. It is still widely used however for evaluating various types of vascular pathologies within the skull.
