These include cancer, heart disease, gastrointestinal, endocrine, or neurological disorders, and other conditions. Nuclear medicine exams pinpoint molecular activity. This gives them the potential to find disease in its earliest stages. They can also show whether you are responding to treatment. Nuclear medicine is noninvasive. Except for intravenous injections, it is usually painless. These tests use radioactive materials called radiopharmaceuticals or radiotracers to help diagnose and assess medical conditions.
Radiotracers are molecules linked to, or "labeled" with, a small amount of radioactive material. They accumulate in tumors or regions of inflammation. They can also bind to specific proteins in the body. The most common radiotracer is F fluorodeoxyglucose FDG , a molecule similar to glucose.
Cancer cells are more metabolically active and may absorb glucose at a higher rate. This higher rate can be seen on PET scans.
This allows your doctor to detect disease before it may be seen on other imaging tests. FDG is just one of many radiotracers in use or in development. You will usually receive the radiotracer in an injection.
Or you may swallow it or inhale it as a gas, depending on the exam. It accumulates in the area under examination. A special camera detects gamma ray emissions from the radiotracer. The camera and a computer produce pictures and supply molecular information. Many imaging centers combine nuclear medicine images with computed tomography CT or magnetic resonance imaging MRI to produce special views.
Doctors call this image fusion or co-registration. Image fusion allows the doctor to connect and interpret information from two different exams on one image. This leads to more precise information and a more exact diagnosis. It is not currently available everywhere. A PET scan measures important body functions, such as metabolism.
It helps doctors evaluate how well organs and tissues are functioning. CT imaging uses special x-ray equipment, and in some cases a contrast material , to produce multiple images of the inside of the body. A radiologist views and interprets these images on a computer monitor. CT imaging provides excellent anatomic information. These combined scans help pinpoint abnormal metabolic activity and may provide more accurate diagnoses than the two scans performed separately.
Women should always tell their doctor and technologist if they are pregnant or breastfeeding. See the Safety in X-ray, Interventional Radiology and Nuclear Medicine Procedures page for more information about pregnancy and breastfeeding related to nuclear medicine imaging. Tell the doctor and your exam technologist about any medications you are taking, including vitamins and herbal supplements.
List any allergies, recent illnesses, and other medical conditions. You will receive specific instructions based on the type of your PET scan.
Diabetic patients will receive special instructions to prepare for this exam. If you are breastfeeding at the time of the exam, ask your radiologist or doctor how to proceed. It may help to pump breast milk ahead of time and keep it on hand for use until the PET radiotracer and CT contrast material are no longer in your body.
Leave metal objects including jewelry, eyeglasses, dentures and hairpins at home as they may affect the CT images. You may need to remove hearing aids and removable dental work. Eating may alter the distribution of the PET tracer in your body and can lead to a suboptimal scan. This could require you to repeat the scan on another day, so following instructions regarding eating is very important. You should not drink any liquids containing sugars or calories for several hours before the scan.
Instead, you are encouraged to drink water. If you are diabetic, your doctor may give you special instructions. Tell your doctor about all the medications you are taking. List any allergies, especially to contrast materials or iodine. Your doctor will check for any conditions you may have that could increase the risk of receiving intravenous contrast material.
A PET scanner is a large machine with a round, donut-shaped hole in the middle. Multiple rings of detectors inside the machine record the energy emissions from the radiotracer in your body.
The CT scanner is typically a large, donut-shaped machine with a short tunnel in the center. You will lie on a narrow table that slides in and out of this short tunnel. Rotating around you, the x-ray tube and electronic x-ray detectors are located opposite each other in a ring, called a gantry. The computer workstation that processes the imaging information is in a separate control room. This is where the technologist operates the scanner and monitors your exam in direct visual contact.
The technologist will be able to hear and talk to you using a speaker and microphone. The amount of radioactive material used in the test is very small. Because disease is a biological process and PET is a biological imaging examination, PET can detect and stage most cancers, often before they are evident through other tests.
Cancer cells show up brighter in the picture because they use more glucose than normal tissues. Clinical research data has proven that PET is superior to conventional imaging in the diagnosis, staging, and surveillance restaging of various types of cancers. Share on Facebook. Notice: Users may be experiencing issues with displaying some pages on stanfordhealthcare.
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New to MyHealth? Manage Your Care From Anywhere. Activate Account. Create a New Account. Forgot Username or Password? What to Expect. PET scan of the heart A PET scan can also give information about the flow of blood through the coronary arteries to the heart muscle.
Your scan may have to be cancelled if you're late. It's a good idea to wear loose, comfortable clothes. It may be possible to wear these during the scan, although sometimes you may be asked to change into a hospital gown. Avoid wearing jewellery and clothes that have metal parts, such as zips, because these will need to be removed. If you're claustrophobic, ask the hospital staff before the day of the scan about the possibility of having a mild sedative to help you relax.
The radiotracer is injected into a vein in your arm or hand about an hour before your scan, as it takes time for it to reach the right cells in your body.
It's important to relax, keep as still as possible, and avoid talking while you wait because moving and speaking can affect where the radiotracer goes in your body. The scan usually takes 30 to 60 minutes. Having the scan is completely painless, but you may feel uncomfortable lying still for this long. You shouldn't experience any side effects after having a PET scan and can usually go home the same day. The results of your scan won't usually be available on the same day.
They'll be sent to your specialist to be discussed at your next appointment. Any exposure to radiation carries a very small risk of potential tissue damage that could cause cancer at a later date.
The radiotracer becomes quickly less radioactive over time and will usually be passed out of your body naturally within a few hours.
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