What are CT angiography and perfusion CT?
These specialized tests use the CT scanner to take pictures of the brain as a contrast dye is injected into your bloodstream. The dye helps to produce a more detailed image of the blood vessels in the brain. CT angiography is a less invasive alternative to conventional angiography because the dye is injected through a needle into a vein in your arm or hand. Conventional angiography requires a long, thin tube called a catheter be inserted through an incision in your groin or arm and guided through your arteries to the head. CT angiography is more accurate than normal CT at determining where the blockage is, how much brain tissue is permanently damaged, and how well smaller vessels are routing blood flow around the blockage.2 A perfusion CT scan uses the dye to produce a map of all the blood in your brain. This can help doctors identify the location of reduced blood flow that is responsible for stroke symptoms. Certain types of perfusion CT can also measure how quickly your blood is movi
