Tumors can be highly vascularized structures and this large amount of blood vessels can lead to excessive bleeding during surgical removal. In some cases, patients undergoing a surgical resection of a tumor of the head, neck, or spine are referred for a procedure to reduce blood supply to the tumor. This procedure is known as pre-operative tumor embolization. A small catheter is advanced under x-ray guidance into the region of the blood vessels supplying a tumor. After angiographic evaluation of the blood supply, blood vessels can be intentionally plugged by injecting small particles or glue-like material into the arteries. This technique aims to “devascularize,” the tumor and reduce intra-operative bleeding.