The fusion of two sophisticated scanning technologies, positron emission tomography (PET) and computed tomography (CT), shows both metabolic function and anatomical detail in a single exam. This integration provides more accurate information for diagnosing the presence and extent of disease, prescribing treatment and tracking therapy progress. Benefits for this exam include:

  • Allows early diagnosis of disease, often before anatomical changes or medical symptoms occur
  • Provides accurate disease staging and localization for biopsy, surgery or treatment planning
  • Assesses response to and effectiveness of treatments
  • Detects residual or recurrent disease
  • Helps avoid invasive diagnostic procedures

PET/CT is one of the most powerful diagnostic tools available today for detecting diseases before anatomical changes or medical symptoms occur. Its imaging capabilities permit accurate diagnosis, staging and monitoring for a variety of cancers. In addition, PET/CT provides important diagnostic information on heart disease and neurological disorders, such as Alzheimer’s disease.

What is a PET / CT scan?

By combining the imaging capabilities of PET and CT, the PET/CT fusion provides more definitive information about the human body than either method alone. The highly sensitive PET portion of the scan detects changes in cellular function — how your cells are utilizing nutrients such as sugar and oxygen. Since these functional changes typically take place before anatomical changes or medical symptoms occur, PET exam data enables your physician to diagnose disease at an earlier stage.

The CT function acquires very detailed pictures of your body’s anatomical structures including bone and soft tissues. Using a computer, these 2D images can be presented in 3D for in-depth clinical evaluation. When these two scans are fused together, metabolic changes can be viewed in the proper anatomical context of your body. The findings a PET/CT offers allows your doctor to more accurately diagnose problems, determine the extent of disease, prescribe treatment and track progress.

Exam Preparation

  • Prior to your scheduled appointment, Overlake will call you to discuss specific instructions, review your health and insurance information and answer any questions.
  • If you’ve had an allergic reaction to a contrast in any prior medical imaging exam, please notify our staff before your appointment.
  • Do not do any strenuous activities, heavy lifting or exercise 24 hours prior to your exam. Excessive muscular activity may interfere with the interpretation of your study.
  • Continue to take prescribed medications (with water) on the day of the exam, unless instructed otherwise by your physician.
  • Because elevated blood sugar can affect your exam results, we recommend you follow a high protein diet with no or limited quantities (3 grams maximum per day) of carbohydrates at least 24 hours prior to your exam day. Do not eat or drink anything except water for at least 12 hours prior to the exam as test results are affected by your blood sugar. Also, do not chew gum. Please follow a protein diet with no carbohydrates for 24 hours prior to beginning your PET/CT exam preparation.
  • Be well hydrated — drink plenty of water the day before and the day of your exam.
  • If you are a diabetic, please notify our staff to obtain special instructions.
  • If you take insulin to control your diabetes, you will be scheduled for an early morning appointment since you must withhold taking your insulin prior to the exam.
  • Please bring all of your prior medical imaging studies (CT, MRI, PET, ultrasound, etc.) with you on the day of your exam.
  • Wear warm, comfortable clothing free of metal zippers, snaps, etc.
  • Leave your valuables at home. All jewelry, hair pins and clips must be removed prior to the exam.
  • Patients weighing over 400 pounds, or females who are pregnant or breastfeeding are unable to be scanned.
  • Please arrive 15 minutes prior to your exam.

Note: A radiopharmaceutical FDG has to be prepared specifically for your exam procedure the day of the study. If you cannot keep your appointment, please notify us at least 24 hours in advance, otherwise you may be charged the $350 fee for the FDG dose.

During the Exam

  • PET/CT exams are completely painless with no side effects.
  • When you arrive, our PET/CT Technologist will discuss the procedure with you and answer any questions.
  • Plan on spending a total of 2 - 3 hours at Overlake. The actual scan takes approximately 20 - 40 minutes. The scan may be longer if your doctor has ordered one or more contrast CT scans to accompany your PET/CT scan.
  • Your blood sugar will be tested and if the levels are acceptable, the procedure will begin.
  • A small IV will be started in your arm for an injection of a small amount of radioactive glucose or sugar. (Called a radiopharmaceutical FDG — a fluoride radioisotope bound up to a high molecular weight glucose.)
  • You will rest in a special quiet area for 45 - 60 minutes as the FDG circulates throughout the body.
  • After emptying your bladder, you will lie down on a comfortable scanner bed.
  • The table will move slowly through the donut-shaped PET/CT scanner as it acquires the information needed to generate diagnostic images.
  • You will be asked to lie still and breathe normally during the scan because movement can interfere with results.
  • Your PET/CT will be reviewed to make certain that all images are complete and no delay imaging is required.
  • After your scan, you will get up from the scanner bed and check out with the receptionist.

After the Exam

  • You may leave as soon as the exam is completed.
  • If you were given Valium before or during the scan, you will need someone to drive you home.
  • Your normal activity and eating habits may be resumed.
  • Drinking plenty of water and other fluids after the exam will help flush the FDG from your body.
  • Your PET/CT scan will be interpreted by a board certified radiologist with specialized training in PET/CT imaging.
  • Your referring physician will receive a report and pictures detailing the findings of your exam within 48 hours. You should contact your doctor to discuss the results.

Common Reasons for the Exam

PET/CT scanning is helps to better understand the fundamental nature of many diseases. Its ability to pinpoint abnormal metabolic activity in cells with a precise anatomical reference is revolutionizing patient care in several key areas. 

Oncology Applications

  • Differentiate benign from malignant tumors in suspicious areas
  • Survey whole body for cancer that may have spread
  • Monitor success of therapy
  • Assess tumor aggressiveness

Neurology Applications

  • Diagnose Alzheimer’s disease, dementia, stroke and brain tumors
  • Determine the location of epileptic seizures prior to surgery
  • Diagnose movement disorders such as Parkinson’s disease