PET-CT, Positron Emission Tomography-Computed Tomography

Positron Emission Tomography-Computed Tomography, also called a PET-CT scan, is the most advanced imaging technique that combines nuclear medicine and computed tomography technology to produce three dimensional images of the functional processes in the body with accurate anatomic clarity.

What is a PET-CT scan?
PET-CT, which stands for Positron Emission Tomography-Computed Tomography, is a procedure that adds an important new dimension to a physician’s ability to diagnose and manage disease. Instead of detecting changes in the physical size or structure of internal organs, as other imaging technologies do, PET-CT detects changes in cellular function – demonstrating, for example, how your cells are utilizing nutrients like sugar and oxygen. Since these functional changes may take place before physical changes occur, PET-CT can often provide information enabling your physician to make an earlier diagnosis of disease or abnormalities. If these diseases or abnormalities have already been detected by an imaging exam such as a CT or MRI study, PET-CT can often characterize the cellular function early in the course of the disease and help differentiate nonmalignant diseases from malignant ones and monitor your response to treatments. A PET-CT scanner is similar to a CT scanner in appearance. The pictures it takes show the utilization of a small amount of a radioactive material, such as sugar, in your body. The radioactive dose, fluorine-18 fluorodeoxyglucose (FDG), you will receive is injected into a vein. The pictures for the PET-CT scan usually take approximately 30-40 minutes for your whole body. For these pictures you will need to lie flat on your back and be still. Images from your scan are reviewed by board-certified, fellowship-trained radiologists and correlated with your history and other available radiology studies you may have.

Are there risks associated with PET-CT?
You are exposed to a small amount of radiation that is not considered to be a threat to your health. The radiation that you receive is roughly equivalent to what you would receive from a couple of chest X-rays and a CT. Rest assured, that the radiopharmaceuticals used in PET-CT have a very short half-life, meaning that they do not stay in your body very long. We ask that, for the remainder of the day, you drink plenty of water and empty your bladder often. This will help rid your body of any residual radiotracer or barium from the study. However, we would advise that you wait a few hours after you leave before any close interaction with infants or pregnant women. Pregnant or breast-feeding women should not have a PET-CT scan without discussing the risks with their physician.

How do I prepare for a PET scan?
You will be given 2 bottles of flavored oral Barium solution and be asked to drink ½ bottle every 30 minutes beginning 90 minutes prior to your exam. Some people might experience mild abdominal discomfort and diarrhea from the barium, which will quickly pass. Other than the aforementioned barium solution, you should have nothing to eat or drink, including candy and gum, except for water for at least four (4) hours prior to your appointment. Avoid any strenuous activity the day before and the day of your exam. Excessive muscular activity may interfere with the interpretation of your scan. If you need to take medications, they can be taken with water. If there are medications that need to be taken with food, you may have a few saltine crackers. Diabetic patients need to regulate their sugar levels to as close to normal as possible because the glucose in the blood competes with the radioactive glucose that we will be administering. The blood glucose level needs to be less than 150 at the time of your injection. If your blood glucose level is above 150, please contact us prior to coming in for your scan so we can work with you and your physician to obtain a high quality scan.

What should I bring with me for a PET-CT scan?
If you have GCM radiology, please let us know and we will be able to obtain them for comparison. If you have X-rays, CTs, MRIs, or Nuclear Medicine studies from anywhere else, please bring them with you. If you need medications for pain, anxiety, or claustrophobia please bring them with you to take prior to your scan.

What happens once I get there?
Please arrive 30 minutes prior to your appointment. Upon arrival you will be asked to complete a brief medical history questionnaire or you can download this form at home and bring it with you. You will need to provide your medical insurance information as well. A technologist will escort you to the PET-CT area where you will be asked to change into a gown and relax in a recliner chair. We will review your medical history and explain the procedure to you, then perform a finger stick to obtain your blood sugar level. After we obtain your blood sugar level, you will receive an intravenous injection (just like getting your blood drawn) of our imaging agent and be instructed to relax quietly in the chair for approximately 60 minutes so the injected material can distribute itself throughout your body.

What will the scan be like and how long does it take?
When you are ready for scanning, you will lie on a comfortable table that moves slowly through the ring-like PET-CT scanner as it acquires the pictures. We will ask you to lie very still and breathe normally, because any movement can interfere with the results of the scan. You should not feel anything during the scan and may only hear an occasional slight humming during a short portion of the scan. The scan itself only takes about 30-40 minutes; however plan to spend two to three hours with us from the time you arrive until the time you leave. You will be free to leave immediately after the scan. Unless you have received special instructions, you will be able to eat and drink normally; in fact drinking lots of fluids will help excrete any of the radiopharmaceutical that may still be in your system.

When will I receive the results of the PET-CT scan?
The results of the PET-CT scan will be faxed or mailed to your physician, usually within 24 hours of your study. Your referring physician will give you the PET-CT scan results.

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