Rochester Radiology | Imaging with Insight | For Our Patients: Healthcare Information Links

Sanjeev Taneja, MD, joined Rochester Radiology as Chief of Nuclear Medicine. Board-certified and a specialist in Nuclear Radiology, Dr. Taneja works at Rochester General Hospital and at the 1415 Portland Avenue Medical Office Building attached to Rochester General Hospital.

The World Health Organization reports that a substantial number of Americans will be diagnosed with some form of cancer during his or her lifetime. A new technology, PET/CT, enables early diagnosis and treatment of a variety of cancers. PET/CT scans are also used to diagnose certain conditions of the heart and brain, including Alzheimer’s disease.

Positron Emission Tomography (PET) and Computerized Tomography (CT) are separate technologies used to obtain information about a section of the body. The combination of these two technologies, PET/CT, provides a more accurate and complete image of abnormal tissue in a single scan. PET/CT images show the location, size, structure, and metabolism, or growth rate, of cancerous cells. Armed with such valuable and comprehensive information early on, physicians can determine the best treatment for their patients.

PET/CT scans are making critical contributions in oncology, cardiology, neurology, and psychiatry.

•	In oncology, PET/CT is valuable in diagnosing and staging many cancers, including lung, breast, head and neck, cervical, thyroid, esophageal, recurrent colorectal cancer, lymphoma, melanoma, recurrent brain tumors, and in tumor-therapy monitoring. PET/CT is also used to assess the effectiveness of treatments such as chemotherapy.
•	In the area of cardiology, PET/CT helps in the diagnosis of coronary artery disease and myocardial viability.
•	Physicians who are treating patients with neurological and psychiatric conditions find PET/CT an important tool for diagnosing Parkinson’s, Alzheimer’s, and Huntington’s diseases. PET/CT also helps physicians to determine the extent of epilepsy and stroke.

What is a PET/CT scan?
PET/CT scans are safe, noninvasive, and painless. Before the scan, the patient receives an injection of a radioactive sugar, or “tracer” (FDG). The tracer mimics substances found naturally in the body and accumulates in diseased or abnormal cells. It’s very important for the patient to arrive on time to receive the proper dose of the radioactive tracer used for the scan.

The scanner uses specialized software, cameras, and X-rays to create accurate, detailed images of the targeted area. The images are displayed on a computer monitor.

A PET/CT scan provides three kinds of images:

•	PET images of the function and metabolism of the targeted cells
•	CT images of the anatomy and structure of the affected organs and tissues, including the dimension of vessels, lymph nodes, and organ systems
•	Merged images of all the PET and CT information

Benefits of PET/CT exams

•	Accuracy
•	Early detection of disease
•	Cost effectiveness
•	Single test or scan rather than several
•	Possibly avoiding surgery

PET/CT represents the gold standard in cancer care for the foreseeable future. Early detection and treatment offer patients the greatest chance at recovery.

What can the patient expect during a PET/CT scan?
Very little preparation is needed. Typically, the patient is asked not to exercise or eat for 6–8 hours before the exam; however, water is allowed. Unless the patient is diabetic, usual medications may be taken.

Those who are diabetic should not inject their regular doses of insulin because the increased glucose levels can affect the results of the exam. These patients should request instructions from their physician regarding food and insulin requirements.

At the examining facility, the patient changes into a hospital gown, receives the tracer injection, and then rests for 30–60 minutes while the tracer travels through the body.

Then the technologist positions the patient in the scanner, lying flat within the scanner with arms above the head. The time of the scan itself varies depending on the patient’s height and the size of the area of interest, but typically lasts from 20–40 minutes. The CT portion of the exam takes place first. The patient might be asked to hold his/her breath for a few seconds at this time. It’s important that the patient not move for the duration of the scan.

The entire visit takes 1½–2 hours. After the scan, the patient can resume normal activity. The tracer leaves the body, but the patient can drink water to clear the body more quickly.

Are there any special considerations before having a PET/CT scan?
Physicians should be consulted before requesting a PET/CT scan if the patient:

•	is or may be pregnant
•	is diabetic
•	is unsure whether to take medication
•	has recently undergone radiation therapy

What happens with the PET/CT images?
The computer software generates the PET/CT images, which are read by a trained radiologist, who compares them to previous PET scans, MRIs, X-rays, and other studies in the patient’s medical record.

The radiologist then lines up the CT images at the top of the computer screen, the PET images in the middle, and the fused images on the bottom. The vivid 3-D images can be rotated and manipulated on computer screens.

The radiologist looks for areas in which glucose is used. These areas appear as dark spots in the brain, heart, and muscles—as well as in tumors. The radiologist’s report is forwarded to the requesting physician as soon as available. This information helps the doctor make better decisions on whether surgery is necessary, or whether chemotherapy or radiation therapy is a more viable option.

Note A graphic or graphics will be provided to illustrate what the CT images, PET images, and fused images show.

Does insurance cover a PET/CT scan?
Prior approval by some insurance companies is required for a PET/CT scan. For Blue Choice or Preferred Care, prior approval is needed. This should be arranged through the requesting physician. Other questions about insurance coverage should be directed to the patient’s insurance company or health plan administrator.

What does the physician do with the results?
In oncology, physicians use PET/CT reports to differentiate between benign and malignant growths, determine the staging and restaging of malignancies, detect malignant recurrence, and monitor therapies, thus eliminating the need for unnecessary tests in the future.

For example, PET/CT imaging improves the accuracy of determining the stage of non-small cell lung cancer. Since treatment depends on the stage of the cancer, the accuracy of detection is imperative to determine the most effective type of treatment.

Not only are PET/CT scans used in planning surgeries, but they can also reveal unanticipated extensive disease, for which surgery would not be beneficial.

In gerontology, PET/CT reports are used to differentiate Alzheimer’s disease from fronto-temporal dementia (FTD). Each of these diseases is treated differently. Early detection and treatment slow the disease’s progress, improve quality of life, and subsequently reduce healthcare costs.

With information from the PET/CT scan, the patient and physician are better able to consider the appropriate treatment and most suitable follow-up.

For more information
MedLinePlus
RadiologyInfo
Radiological Society of North America
Medical News Today article