A biopsy of the temporal artery is the definitive procedure for diagnosing giant cell arteritis. Doppler ultrasonography is occasionally used to locate the part of the temporal artery to be biopsied. After a local anesthetic is injected, a shallow incision is made directly over the artery, and a segment of the artery at least 1 inch (2.5 centimeters) long is removed. The incision is then stitched up.