Obtaining a symptom history and performing a neurological examination will be your doctor’s first steps in making a diagnosis. Magnetic resonance imaging (MRI), done both with and without a contrast dye, is then used to identify the presence of a tumor in the brain. The contrast dye is given intravenously (into the vein) to enhance the pictures. By concentrating in abnormal tissue, the dye makes a tumor appear much brighter than other areas. If a tumor suspected of being a medulloblastoma is identified, an MRI of the entire spine can be done to look for tumor in that area. PET (positron emission tomography) and MRS (magnetic resonance spectroscopy) may be used to determine if what is seen on the scan is growing, live tumor as opposed to radiation effects or non growing tissue.
While scans provide important and intricate details, microscopic examination of tissue obtained during a surgical procedure, such as a biopsy or tumor removal, confirms the diagnosis. The pathologist, a doctor who specializes in studying tissue samples, will be looking for cell patterns that identify the tumor type. A pathology report usually takes about a week to be completed. It is sent to your neurosurgeon’s office, and the results then shared with you.