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Key imaging substance available to hospitals, clinics (8-31-99)

The Research Imaging Center at The University of Texas Health Science Center at San Antonio has received state clearance to distribute an imaging agent previously not available to area hospitals and diagnostic clinics.

The agent, called 18Fluorodeoxyglucose or 18FDG, is a "radiotracer" that can be used to demonstrate normal and abnormal function in various organs of the body. Clinical applications include extremely sensitive detection of cancer, heart abnormalities and epilepsy.

The Bureau of Radiation Control in Austin gave final approval to the Health Science Center's license application in late July, ending a three-year application process that included passage of enabling legislation by the federal government (the FDA Reform Act of 1997) and a subsequent rewrite of state regulations. The Research Imaging Center (RIC) will team with San Antonio-based Syncor to distribute the radiotracer.

18FDG is made with radioactivity in an instrument called a cyclotron. The RIC's cyclotron, purchased in 1991 by the South Texas Veterans Health Care System and the U.S. Department of Defense, is a $3 million particle accelerator.

"A radiotracer enables us to see metabolic processes," said Peter T. Fox, M.D., director of the RIC. "It is given in trace amounts which are barely detectable but enough to do imaging. It is called ‘radio' because it gives off x-rays, and ‘tracer' because it gives off trace amounts. These amounts are too small to interfere or interact with the physiological processes of the body. We are just getting into the system to measure it."

The RIC is a research facility and the only institution in Texas distributing 18FDG. "Our reason for obtaining this license is to allow other sites to do clinical work with these tracers," Dr. Fox said.

"The chief clinical use of 18FDG is in determining the stage, or severity, of cancer. 18FDG measures metabolic rate; tumors have a higher metabolic rate than surrounding tissue. 18FDG can detect tumors that are microscopic and can detect those that have metastasized, or spread. The second most common clinical application is evaluation of cardiac muscle viability--the strength of the heart wall."

Hospitals and clinics with PET (Positron Emission Tomography) systems or 18FDG-compatible SPECT (Single Photon Emission Computed Tomography) systems will be able to utilize 18FDG in providing billable clinical care. These imaging systems range in cost from $500,000 to $2 million. The South Texas Veterans Health Care System and the Department of Defense jointly purchased the Research Imaging Center's PET system in 1991.

"Sites will need a scanner compatible with this tracer," Dr. Fox said. "The South Texas Veterans Health Care System, Brooke Army Medical Center and the Baptist Health System are among those that already have 18FDG-compatible SPECT imaging systems."

Congress deregulated use of radiotracers as part of the FDA (U.S. Food and Drug Administration) Reform Act. "States responded by changing their rules," Dr. Fox said. "The state of Texas did so in 1998. We applied for our license in August 1998 and received final approval in late July. We had been trying to receive authorization to distribute 18FDG for years.

"People at other hospitals had asked us to distribute this radiotracer to them, but we couldn't do it. It literally took an act of Congress to get things moving. We reformatted our license application in January 1999 because the standards were changed after our initial submission."

Acquisition of the tracer represents a new "business opportunity for many medical institutions around this area," he said. "It will require outlay for a PET or 18FDG-compatible SPECT system, but the institutions will be able to offer new imaging procedures and interpret the scans."

The Research Imaging Center utilizes imaging instruments to conduct the latest research studies and to add to scientific literature in a host of areas, such as brain mapping, neurological disorders, learning, memory and language. Providing clinical service is not the RIC's focus.

"We're not trying to corner the market on this procedure," Dr. Fox said. "We could do the clinical scanning, but we prefer to give the medical community at large an equal opportunity to provide this service to the patient."

Radiotracer scanning is in high demand wherever it is available, he said. Other institutions that provide clinical PET include Duke University and The University of California at Los Angeles.

The RIC has begun training future providers and has contracts to distribute 18FDG to the Baptist Health System, the South Texas Veterans Health Care System and Hill Country Memorial Hospital in Fredericksburg.

Contact: Will Sansom