PET/CT: Charting the Treatment Course

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This image, captured on Siemens Biograph, illustrates a malignant nodule in the right lung.Technological advances combined with increasing awareness of the benefits of PET/CT among the general physician population has the modality poised for growth. Proponents are gathering the data needed to widely prove the modality’s ability to provide important measures of cancer treatment. The newest generation addresses the growing rate of obesity and indications increase regularly.

“I’ve been a diagnostic radiologist for 32 years and this is the most exciting time in my life to practice PET/CT, says Joe Busch, MD, radiologist at Diagnostic PET/CT Center of Chattanooga in Tennessee. “Practicing oncology with PET/CT is the most exciting thing I’ve ever done in radiology. It changes patients’ lives, changes therapies, and changes what you do to a patient.” Busch notes that 30 percent of the time, the information gathered via PET/CT changes a patient’s course of treatment.

More and more see the benefits

Busch and his colleagues use Siemens Medical Solutions Biograph 6 and Biograph 16 PET/CT scanners. The equipment lets them simultaneously perform diagnostic CT and PET imaging. The PET/CT scanner allows for image correction. “This is true hybrid imaging,” he says. With a 16-slice scanner, he figured “why not use it like a real CT scanner? We do biopsies, therapeutic injections and more.” The primary use is to stage and restage cancer, and measure therapeutic response — measuring both physiology and looking at morphology.

Kevin Berger, MD, director of PET imaging in the department of radiology at Michigan State University in Ann Arbor, agrees that using PET/CT to scan cancer patients often results in important changes to treatment, such as detecting a metastasis that wouldn’t have been found otherwise. His department uses the Discovery PET/CT system from GE Healthcare. “It lets us better define where a patient has disease. That’s why PET has grown — it has been so useful and so critical to making changes and decision-making that affects patients.”

Anthony Larhs, MD, director of nuclear medicine and clinical PET at TRA Medical Imaging in Tacoma, Wash., has been using the Gemini TF PET/CT from Philips Medical Systems since December 2006. Just four or five years ago, only medical or radiation oncologists could talk about this modality, he says. As clinical research has evolved and more meetings have included presentations on PET/CT, more physicians are aware of the benefits of this technology. Many more surgeons and internal medicine physicians are starting to use PET/CT, he says. “It takes a certain amount of time to disseminate the knowledge to the community. That change has partially occurred.”

Gemini TF features TruFlight technology, which identifies the time difference in detection of the two coincident gamma rays to within a billionth of a second (roughly the speed of light) which facilitates calculation for the reconstructed image. TRA is the first facility to install the system west of Denver and only the 28th organization worldwide.

Larhs says that many so-called technological changes are really marketing hype or small changes that don’t justify the purchase of new equipment. TruFlight technology, however, is “quite a tremendous feat. It improves sensitivity by nine times. That’s amazing.” And, contrary to other modalities, TruFlight allows PET/CT imaging to improve as a patient’s size increases. “All imaging modalities deteriorate and cannot perform well if the patient is heavier. We cannot offer the same quality of medicine because we can’t see very well deep inside the body.” Because time-of-flight increases along with the waistline, “we start to see equivalency of medicine” for obese patients. Larhs says that it becomes a social and medical responsibility for clinicians to refer their heavy patients to PET equipment that has time-of-flight capability.

Diagnos PET/CT Imaging is a new facility in Houston, Texas, devoted to PET/CT. Although the vast majority of procedures are for neurological or oncological conditions, the facility has a mix of physicians, including internists, general practitioners and a gastroenterologist. When the facility opened about a year ago, the goal was a tranquil environment in which patients could get the best possible care, says Graham Williams, COO. The group of 20 physicians uses the Sceptre P3 PET/CT system from Hitachi Medical Systems America. “Starting from scratch, it’s apparent you have to educate. PET/CT is little understood by the physician community,” he says, but the market