Unlike CT, MRI does not use radiation. It provides pictures from various angles that can enable doctors to construct a three-dimensional image of the tumor. MRIs are useful during surgery to show tumor bulk and for accurately mapping the brain. PET is not routinely used for diagnosis, but it may help to determine tumor grade after a diagnosis and to distinguish between recurrent tumor cells from dead cells or scar tissue. X-rays of the skull were once standard diagnostic tools but are now performed only when more advanced procedures are not available.
Cerebral angiography involves x-rays of blood vessels in the brain.
The role of angiography in glioma is usually limited to planning surgical removal of a tumor suspected of having a large blood supply. Radionuclide brain scintigraphy uses a radioactive substance that is administered and absorbed by capillaries in the tumor, which are then viewed using imaging techniques. Digital holography, a new technique that provides full three-dimensional mapping, is under investigation. A lumbar puncture is used to obtain a sample of spinal fluid, which is examined for the presence of tumor cells, which indicates that the cancer has spread. If a brain tumor is suspected, a CT scan or MRI should always be performed before a lumbar procedure to be sure the tumor is not pressing on the brain.