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PET Scan

PET Scans

Sibley’s commitment to cancer diagnosis and treatment continues with acquisition of the revolutionary PET scanner made by GE Medical Systems. Positron emission tomography, or PET, is the acknowledged gold standard for medical, surgical and radiation oncology. It enables physicians to diagnose cancer early, treat it with extraordinary precision and monitor treatment efficacy quickly and accurately. The PET services support the medically sophisticated cancer care here at Sibley and serve as a resource to physicians throughout the region.

In addition to cancer care, PET is considered the gold standard for assessing whether a heart muscle is viable for bypass surgery. It can reveal whether the muscle is “asleep” or “dead.” PET is also used in the diagnosis of and treatment planning for intractable seizure disorders, where seizures do not respond to medication.

The How and Why of PET


Both PET and CT enable physicians to see inside the body. Computed tomography, or CT, uses radiation to capture highly detailed, high-resolution anatomic information. It enables physicians to identify lesions and masses that may be malignant.

On the other hand, PET reveals metabolic function at the cellular level. Changes in cell processing are the first indications of cancer, and they are evident long before structural abnormalities develop. Since PET is highly sensitive to even small changes in cell function, it is invaluable in the early diagnosis of cancer.

In order to take advantage of both the anatomic detail offered by CT and the specificity of PET, some physicians have been working with a CT from one machine and a PET scan from another machine. By considering the information from both sets of images, the physician makes a judgment about whether a mass (as indicated by the CT scan) reveals a high level of metabolic activity (as revealed by the PET scan). Doing this well can be difficult — and sometimes impossible — because images from one machine often do not align with images from another machine.

A PET/CT scan performed at one point in time on a single machine provides a fused image that precisely places the information about cellular activity in an accurate anatomical context. According to Frederick P. Smith, M.D., a respected Washington, D.C.-area medical oncologist, PET/CT technology takes the diagnosis and treatment of cancer to a new level.

“We no longer have to make assumptions about what is cancer and what is not. We know for sure and we know early on. We do not have to estimate placement. We can pinpoint it with absolute certainty. This specificity and accuracy lets us define a targeted treatment plan with a very high level of confidence about its potential effectiveness.”
Frederick P. Smith, M.D.
Medical oncologist

Understanding the Technology

PET relies on a tracer called 18FDG. It is a combination of a positron emitter and a glucose analog. Tumor cells take up this tagged glucose look-alike more avidly than other cells and they also hold it more tenaciously. The result is that malignant lesions — even as small as a few millimeters — are dramatically highlighted in a PET scan. With a PET, these “hot” areas are presented in an accurate anatomic context.

PET is a proven tool in the treatment and diagnosis of the following:

  • Lymphoma
  • Lung cancer
  • Colon cancer
  • Esophageal cancer
  • Melanoma
  • Breast cancer
  • Pulmonary nodules
  • Coronary artery disease
  • Intractable seizure disorders