By SARA SELIS
Stanford Hospital & Clinics is the first health-care institution in Northern California to offer patients a powerful new diagnostic imaging system known as PET/CT. This hybrid technology combines the strengths of two well-established imaging modalities in one imaging session to more accurately diagnose and locate cancers while increasing patient comfort.
With PET/CT, Stanford physicians can make more accurate diagnoses, develop more targeted treatment plans, and do better, less-invasive treatment monitoring, which should result in improved patient outcomes, said Gary Glazer, MD, professor and chair of the Department of Radiology. It is particularly useful in cancers of the head and neck, lung, colon, thyroid and breast, along with lymphoma and melanoma.
"Stanford is proud to be known for providing our patients with the latest technology," said Martha Marsh, president and CEO of Stanford Hospital & Clinics. "The PET/CT is an exciting innovation which has the power to save lives by enabling our physicians to make earlier and more accurate diagnoses. We are very pleased to offer this new technology to patients in our area."
A PET/CT scan is noninvasive, painless and takes about 30 minutes. Along with providing better imaging data, it notably increases patient comfort and convenience by reducing the number of scanning sessions a patient must undergo. The procedure is covered by private insurance and Medicare.
PET, or positron emission tomography, monitors the biochemical functioning of cells by detecting how they process certain compounds, such as glucose (sugar). Cancer cells metabolize glucose at a much higher level than normal tissues. By detecting increased glucose use with a high degree of sensitivity, PET identifies cancerous cells — even at an early stage when other modalities may miss them. However, PET cannot pinpoint the exact size and location of tumors to a precision necessary for optimal diagnosis and treatment planning, Glazer said.
CT, or computed tomography, yields a detailed picture of the body’s anatomical structures by taking cross-sectional images or X-ray slices of the body. While CT does an excellent job of depicting structures and anatomy, it may miss small or early stage tumors, Glazer said.
Currently, physicians can overlay the results of PET and CT scans performed separately to identify and locate tumors. However, because a patient may not be positioned identically for both scans, the two images can be difficult to line up exactly, degrading the accuracy of the diagnostic information.
The combined PET/CT machine allows physicians to rapidly perform both scans in one session without having to move the patient. This means physicians can precisely overlay the metabolic data of the PET scan and the detailed anatomic data of the CT scan to pinpoint the location and stage of tumors.
"The availability of PET/CT represents a vast improvement in the way we stage and treat cancer," said Ross McDougall, MD, PhD, professor of radiology and acting chief of nuclear medicine. "This is very exciting technology that puts Stanford at the cutting edge of diagnostic imaging."
Clinical research has shown that in comparison to a PET scan alone, PET/CT technology provides new information that can alter a patient’s treatment plan to better target the cancer in approximately one-third of the cases. In one example, the PET/CT scan of a lung cancer patient revealed not only the original tumor on the lung — which a previous CT scan had found — but an additional tumor the CT missed: a small, early stage lesion in the neck. Based on the CT alone, the physician would have recommended surgery, but the additional tumor found by PET/CT indicated that the cancer had spread and was inoperable. Based on this information, the physician proceeded with radiation therapy, giving the patient a better chance of survival.
"Physicians who have used this love it. They say it’s revolutionized their practice," McDougall said. "Once they’ve seen what PET/CT can do, it changes their whole approach to treatment."
Stanford physicians will use the scanner not only to detect and stage cancers but also to monitor patients’ response to treatment. PET/CT can significantly reduce the number of invasive biopsies normally done for this purpose. "This scanner combines the best of PET with the best of CT, and the sum of the two is clearly greater than its parts," said Robert Herfkens, MD, professor of radiology.
While PET/CT is primarily used in cancer treatment, it also has applications in cardiology and brain imaging, and it will help Stanford physicians better understand the workings of heart disease and such neurological disorders as epilepsy and Parkinson’s disease.
Stanford’s multimillion-dollar PET/CT scanner was manufactured by GE Medical Systems. For additional information or to schedule a patient, please call 723-6884.
Stanford Report, January 29, 2003