It may help to tell whether a tumour is active and whether it is malignant or benign. First you will have a small needle inserted in your arm for the injection. The dose of radiation you receive is no more than a normal X-ray. After your injection, you may be asked to lie quietly in a dark room with your eyes closed. You will then be taken to the scanning room and asked to lie on a couch with the scanning ring around you.
PET scans are only available in a few hospitals.
An angiogram shows blood vessels and may show the position of the tumour. This may be useful information if an operation is planned. When the catheter has been passed into the correct artery, a dye is injected and a series of X-rays is taken as the dye flows through the brain's blood vessels. You may need to be admitted to hospital overnight for the angiogram, as it is usually necessary for you to be sedated or to have an anaesthetic for the test. This is a recording of the electrical activity within the brain.