PET scan (positron emission tomography)
It is a study that is part of nuclear medicine which assesses the amount of glucose (sugar) that the brain uses. Glucose is the brain’s fuel. Every part of the brain regularly uses glucose to function. In patients with partial epilepsy, seizures could be coming from an area that is damaged (e.g. scar tissue) and that has less brain cells. This part of the brain might not consume glucose at all or might use less than the rest of the brain. The PET scan will highlight differently for that part of the brain. Doctors will refer to this part as a “hypometabolic area” since it uses less glucose than the rest of the brain.
Technically, the test involves a “tracer” which is a dye with glucose (18 F deoxy glucose) that emits a low dose of radiation. It is injected when the patient is not having seizures (this is monitored by EEG). That tracer has glucose and because of that it is consumed by the brain cells. After receiving the injection, the patient is taken to the nuclear medicine suite and is scanned. The part of the brain that is damaged will take in less of the tracer and will produce what is called a “cold” (hypometabolic) area on the scan.