The positron emission tomography scan is used to diagnose cancer, assess brain function and diagnose problems with the brain and heart, states MedlinePlus. A radioactive substance is used to create detailed images of the organs.
Before a PET scan begins, a radioactive tracer is introduced to the bloodstream via an IV line, explains MedlinePlus. The patient must wait about an hour for the tissues in his body to absorb the tracer. Once the tracer has had time to collect in the organs, the patient lies on a table that rolls inside the scanner. PET technology picks up signals from the radioactive tracer and uses the signals to produce three-dimensional images of the organs.
Brain PET scans are used to prepare for neurosurgical procedures, check for brain tumors, diagnose Alzheimer's disease or dementia, determine if other types of cancer have spread to the brain and determine if a patient has Parkinson's disease or another neurological disorder, states Healthline.
Lung PET scans are used to determine if a tumor is benign or cancerous, monitor the effects of lung cancer treatment and determine if the cancer has spread elsewhere, reports MedlinePlus. An abnormal result is not always caused by cancer, however; lung inflammation and infections also affect the results of this test.