CTA is CT angiography, and CTA of the brain is specifically for the blood vessels in the brain, and usually also for the blood vessels in the neck. It includes two parts: CT imaging and computerized secondary imaging. When performing computerized secondary imaging, it is necessary to do contrast injection, and through contrast scanning, the blood vessels can be displayed separately, and for general vascular malformations and aneurysms, the sensitivity is much higher than that of magnetic resonance angiography. It is generally used for screening of aneurysms, and is also more sensitive for the diagnosis of Moyamoya disease, and some other vascular malformations. Usually, in the case of patients with cerebral infarction, it can also be used to determine the degree of vascular occlusion in the patient, and specifically which vessel is narrowed or occluded.