PET-CT Frequently Asked Questions

Why are PET and CT used together?

PET/CT represents the next level of diagnostic imaging power for oncology. PET detects metabolic signals in the body while CT provides a detailed picture of the internal anatomy, revealing the location, size, and shape of cellular activity.

Alone, each imaging test is effective for a wide variety of applications. But when the results of PET and CT scans are "fused" together, the combined image provides complete information on cancer location and metabolism.

What are the clinical applications of PET?

Most common applications of PET are in the fields of oncology, cardiology and neurology.

  ONCOLOGY (cancer) is the most important application of PET/CT, providing vital diagnostic information that can alter the course of cancer treatment and sometimes help in avoiding unwarranted surgery. PET and/or PET/CT provide critical information including whether a tumor is malignant; the extent of cancer; whether it has spread to other organs. The scan can also help monitor cancer recurrences, as well as the effectiveness of chemotherapy or radiotherapy.

  CARDIOLOGY (heart) is another important application, where PET provides a high level of accuracy for measurement of myocardial perfusion and viability. This procedure enables the clinician to determine the value and course of treatment for patients with heart disease. Unfortunately, Hawaii Advanced Imaging Institute does not offer heart PET-CT scans due to the lack of the radiopharmaceutical necessary for the scan.

  For NEUROLOGY (brain), PET provides information to differentiate between Frontotemporal Lobe Dementia and Alzheimer's Disease.

How long does the exam take & will it hurt?

In most cases, you will be on the scanner table for about 30 minutes. The scan itself causes no pain. Because the gantry is open, you will be able to see and speak with your exam technologist. An IV line will be started in your hand or arm in order to infuse a radiopharmaceutical.

What is being injected for the scan & why?

For PET scans, a very small amount of a radiopharmaceutical is infused into the bloodstream. The substance contains radioactive molecules that provide imaging information when absorbed, or concentrated in tissue. Areas with rapid cell growth, such as malignant tumors, will show much higher concentrations of the dose than normal healthy tissue. A computer records this information and converts it into pictures for diagnostic purposes.

What is a Radiopharmaceutical?

A radiopharmaceutical is a radioactive drug. The most commonly used PET radiopharmaceutical is FDG, a radioactive form of glucose (sugar). Radiopharmaceuticals are produced by physicists and chemists.

How do I prepare for the exam?

EATING: You are not allowed to eat for 6 hours prior to the exam. You also need to follow a strict no carbohydrate diet for your last meal before the scan. It is essential your blood sugar level be below 180 or the scan cannot be performed.

ALLERGIES: Notify your physician of any allergies before the exam.

MEDICATIONS: We will ask what medications you take when you schedule your appointment. You will be provided further instructions at that time. If you feel you will need sedation or are a diabetic, contact us for further instructions prior to your scheduled appointment.

PREGNANCY: Be sure to inform your physician if you are pregnant.

ACTIVITY DURING THE SCAN: During the scan, we ask that you are in a quiet, resting state. It is extremely important that you lie still throughout the scan.

What happens after the scan?

It is important that you drink water and empty your bladder often for the rest of the day. This will result in a more rapid clearance of radioactivity from your body. You can drive and resume normal activities immediately after leaving the department, unless you have received sedation.

When will I get the final results?

The final results will be given to your referring physician as soon as the images are analyzed, usually within 24 hours.

Will my insurance cover the exam?

Many insurance companies are reimbursing for some PET procedures, including Medicare. Please contact your insurer directly to learn about payment reimbursement.