Integrated PET-CT Scan
An integrated PET-CT scan combines images from a positron emission tomography (PET) scan, a type of nuclear medicine imaging, and a computed tomography (CT) scan, which produces multiple three-dimensional X-ray images (slices). The two types of scans are performed simultaneously on the same machine. The combined scan gives more information than either scan alone would provide because the CT scan provides detailed images of organs and tissues, while the PET scan detects any abnormal activity in the body.
How the Integrated PET-CT Scan Works
In order for a PET scan to create images of organs and tissues, a small amount of a radioactive substance is injected into a vein. The degree of absorption of this substance by organs and tissues is determined by how much energy they use. Since cancer cells use more energy than healthy cells, they absorb more of the radioactive substance. A scanner then detects this substance and produces images of the inside of the body on a computer screen.
Reasons for an Integrated PET-CT Scan
The PET-CT scan is a diagnostic test used to detect and stage cancer. Staging cancer involves pinpointing its location, determining whether and how far it has spread, and whether the malignancy is affecting organ function anywhere in the body.
Cancer staging is important because it helps to:
- To determine the best type of cancer treatment
- Predict as accurate a prognosis as possible
- Locate a precise area for biopsy
- Evaluate efficacy of previous treatment
- Plan radiation treatment
Integrated PET-CT scans are also commonly used for diagnostic purposes in cardiology and neurology and for diagnostic and treatment purposes in oncology.
The Integrated PET-CT Scan Procedure
Before the test begins, patients are asked to remove any jewelry or accessories that may interfere with the scan. Patients are positioned on the examination table to enable the scanner to view the targeted area most accurately and may be strapped in place to maintain proper positioning. If the scan is administered as part of program of radiation therapy, the patient may be fitted with masks or body casts to make sure that the position remains unchanged for the duration of the treatment period.
The radioactive iodine for the PET scan is delivered either orally, by injection, or through an intravenous (IV) line; for the CT scan, contrast dye may also be administered. During the test, the patient is able to communicate with medical professionals through an intercom.
Many patients experience a temporary sensation of heat or itching as the radioactive substance enters the body and may also have a transient metallic taste in the mouth.
During the integrated PET-CT scan, the examination table slides that patient back and forth through a cylindrical tube open on both ends. The first time the table moves quickly through the scanner to establish that the patient's body is appropriately positioned. For the remaining scans, the table moves slowly as the patient undergoes first the CT scans and then the PET scans.
The scan is not painful but patients may experience discomfort from having to remain in one position for a prolonged period, often with the arms raised over the head. At times, patients are instructed to hold their breath. The table may be adjusted to different heights or angles, and patients may experience temporary sensations of heat or a metallic taste in the mouth.
PET-CT scans last for 30 minutes or more, depending on how much of the body is being scanned. After the test, patients can resume all normal activities, but are advised to drink plenty of water to help flush out the radioactive substance and/or contrast dye.
Risks of the PET-CT Scan
The chief risk of this test is radiation exposure. While the radioactive substance remains in the body for only a short time, the CT scan portion of the test exposes the body to considerably more radiation than typical X-rays. Pregnant women and women who are breastfeeding should not undergo this type of scan because of danger to the fetus or infant. Another risk of the PET-CT scan is an adverse reaction to the contrast dye, though this happens rarely. While in most cases, the benefits of the test far outweigh the risks, this matter should always be discussed with the doctor before treatment.
For more information about Integrated PET-CT Scan, Call Arash Padidar's office at 408-918-0405