Biomedical Frontiers: Winter/Spring 1996, Vol.3, No.2
Clinical Applications
PET Provides Answers

A new coordinating staff is helping prepare the Morton A. Kreitchman PET Center for an increase in clinical patient applications. This mirrors a trend in the use of PET scanners throughout the nation, as both health care and health insurance providers come to view PET scans as an accurate, non-invasive, and cost-effective diagnostic method.

"In many cases, a PET scan can provide answers that other imaging technologies can't."

"The clinical use of PET is still a relatively new field, but it is growing rapidly," says Dr. Ernest J. DeSalvo, the new PET clinical coordinator. "In many cases, a PET scan can provide answers that other imaging technologies can't. In fact, 25 to 30 percent of the time, a PET scan changes the way a doctor treats a patient, thereby avoiding, for instance, unnecessary surgery." In February of this year, CPMC contracted Dr. DeSalvo's company, Strategic Outpatient Services, to manage the clinical operations for the scanner.

PET's diagnostic applications in cancer, cardiology, neurology, and psychiatry are especially significant, says Dr. DeSalvo. In cancer, for instance, because the PET has a resolution of 5 or 6 millimeters, it can pick up a clump of cancerous cells that are less than 1 centimeter wide.

Abnormal whole body PET scan demonstrating a patient with a melanoma.

PET scan of the brain utilized to rule out tumor recurrence.

CPMC researchers are now instituting a study using PET to detect lymph node involvement for women with breast cancer who are at high risk for nodal metastases, according to Dr. Ronald Van Heertum, co-medical director (with Dr. Paul Cannon) of the Kreitchman PET Center, vice chairman of radiology, and director of nuclear medicine. Another study is investigating the use of PET to detect mediastinal lymph node involvement in lung cancer. "CT scans are only about 50 percent accurate for this application," says Dr. Van Heertum.

Cardiac PET study showing decreased perfusion of area of myocardium.

In cardiology, PET is now commonly used to determine the extent of damage caused by coronary artery disease, determine whether patients will benefit from revascularization or need a transplant, and to determine if patients who have undergone revascularization but have developed recurrent chest discomfort are ischemic. "PET is the gold standard for determining myocardial viability," says Dr. Roxanne A. Rodney, assistant professor of clinical medicine and associate director of nuclear cardiology.

In neurology, PET scans are the only way to differentiate recurrent brain tumors from radiation fibrosis or necrosis. Furthermore, a PET scan is the best way to localize an area of the brain that has been causing epileptic seizures that can't be controlled by medications. (In these cases, the area is surgically removed.)

In psychiatry, clinical applications of PET are just coming to light. In a study in the February issue of the American Journal of Psychiatry, Dr. J. John Mann, professor of psychiatry, used PET to provide the first direct visualization of blunted regional brain responses to serotonin release in the brains of patients with major depression.

"This approach holds much promise for the diagnosis and treatment of depression," says Dr. Mann. "In addition, it's conceivable that the same strategy could be applied to other psychiatric disorders such as schizophrenia, anxiety disorders, obsessive-compulsive disorder, and Alzheimer's disease."