Positron Emission Tomography (PET)

What is Positron Emission Tomography (PET/CT)?
Positron Emission Tomography (PET/CT) produces cross-sectional whole body images of metabolic function.  A diseased organ may use greater or lesser amounts of energy or glucose than normal organs, and diagnoses can be made from the amount of metabolic activity measured by a PET/CT scan.  Because malignant tumors use more energy than normal tissues, PET/CT is particularly useful for the diagnosis and staging of cancer, and to determine the effectiveness of treatment.

The PET Center at Georgetown University Hospital
The PET/CT Center staff works closely with physicians at the Lombardi Comprehensive Cancer Center and with Georgetown Hospital ’s Department of Radiation Oncology.

The camera at Georgetown University Hospital is a dedicated PET/CT scanner that meets all of Medicare’s current requirements and is ACR accredited.

HOW TO SCHEDULE A PET SCAN
A PET/CT scan requires a physician referral. To schedule a scan at the PET Center at Georgetown University Hospital call 202-444-3363.

PET/CT and CANCER
PET is used approximately 90% of the time for tumor imaging. Because cancer cells tend to have a higher metabolic rate than normal cells, a PET/CT scan can detect a cancerous tumor even in the very early stages, when the tumor isn’t large enough to be detected by other means, such as CT or MRI alone. It can tell whether tissue is cancerous or benign, important in situations where there could be scar tissue from surgery or radiation therapy

PET/CT can also be used to determine whether a course of treatment is working, by determining, for example, whether a surgical procedure or chemotherapy was successful in removing all cancerous tissue

How a PET/CT Scan Works
In a PET/CT scan, the patient is injected with a radioactive chemical, or tracer, attached to glucose, which is a sugar that cells use for energy. As the tracer spreads throughout the body, areas that have a high rate of metabolic activity absorb more of the tracer than areas of lower activity. As the tracer chemical decays, it releases positrons whose emissions are detected by sensors in the scanner. The computer assembles the signals it receives into an image that maps out the different levels of activity throughout the body. In areas of higher-than-normal metabolic activity, the tracer is more concentrated and shows up as a "hot" spot on the PET scan.

PET/CT and Diagnostic CT

At the Georgetown PET/CT center our patients can have both a PET/CT and diagnostic CT completed within one visit.  The radiology department and the nuclear medicine department are working together to increase patient convenience and to ensure the most accurate information.  

Diagnostic Computed Tomography or CT scan creates very clear two-dimensional images of the brain and other parts of your body that cannot be seen on regular X-rays. In many cases a contrast is injected to highlight certain tissues for closer examination. A diagnostic CT provides detailed information about the location, size, and shape of lesions or growths in the body.

Other Uses of PET/CT
PET is also used to image neurological disorders such as Alzheimer’s disease and epilepsy. Because certain brain cells in Alzheimer's patients have low metabolic rates, they show up as dark spots in a PET scan. Similarly, in cardiac patients, PET can help determine whether an area of the heart has died or whether cardiac surgery may improve heart function.