It is often used in the brain because it can show up many different types of diseases. It has also been done on a breast PET scanner, a lung PET scanner or a heart PET scanner. It looks at the blood flow coming from or to the different organs.
The PET scanner uses a small quantity of radioactive tracer, given through a vein in your arm. The tracer collects in all organs and tissues and helps the radiologist define areas of concern within the body relatively clearly.
The tracer is absorbed in the body over a period of one hour. Then you will lie on a narrow table that goes through the scanner. The PET scanner detects signals from the tracer and turns them into three-dimensional images that the radiologist reads off a computer scan.
It is important to lie still during the exam so the images don’t get blurry. Certain tests take longer than others. A brain PET scan looks at how the brain and tissues are working. CT scans and MRI scans are used alongside MRI scanners. The difference between the scans is that the PET scan shows both the structure and function of the brain on the scanner.
This is a test that can take up to 30 minutes to two hours, depending on the area being scanned.
Sometimes you may be asked to refrain from eating and drinking within 4-6 hours prior to the exam. Water is fine. Speak to your healthcare provider if you have claustrophobia because you could get medication to control your anxiety, if you might be pregnant, if you have allergies to contrast dye or if you take insulin for diabetes. Tell the provider what medications you are taking, even those purchased without a prescription. The only part of a PET scan that hurts is the needle for the IV tracer.
The test itself is relatively painless but the bed itself may be cold or hard. You will be able to use an intercom to speak to the technician or nurse. You will only require some recovery time if you were given a relaxation medicine.
The PET scan is able to show the exact size, shape and functionality of the brain so the doctor can tell how well the brain is working. It is considered a superior test to the CT scan alone or the MRI examination. It can diagnose cancer, help a patient prepare for epilepsy surgery, diagnose movement disorders, diagnose dementia and other diseases.
It may take several serial PET scans to see whether or not a specific treatment worked. In a normal test, the tracer is taken up in normal amounts throughout the brain. An abnormal test looks like unusual amounts of tracer are taken up in different areas.
It can show a change in the position, shape or size of the brain, cancer on the brain, infection or brain dysfunction.
The risks of having a PET scan are low. You are getting only the amount of radiation as is gotten in most CT scans. The radiation doesn’t last long within the body. Unborn infants are more sensitive to the radiation in a PET scan so this might have to be avoided if at all possible.
An unlikely allergic reaction can happen to the radioactive substance and some will have pain, swelling or redness at the sight of the infection.
False positive or negative results can be seen if a person is diabetic and has abnormal blood sugar or insulin levels. PET scans are usually done along with a CT scan at the same time.