Many brain tumors have a risk of recurrence. If the cancer does return, it is important that additional treatment begin immediately. This is also where PET can help.
MR images show changes in the structure of the brain...but these changes may be side effects from previous treatments, such as surgery or radiation. Because PET shows the activity levels of cells, it is the most accurate way of determining whether the cancer has returned. PET scans may also be very helpful in assessing the response of the brain tumor to treatment.