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PET/CT Scanners Offer View To The Future
A new imaging device in the Indiana University Department of Radiology is making it easier for physicians to diagnose and treat cancer and other diseases.
 The Indiana University School of Medicine was one of the first three institutions in the nation to receive a PET/CT fusion imaging system. The Siemens Biograph system was installed at IU in December 2001, and already, physicians are looking to the future.
The state-of-the-art diagnostic scanner can give radiologists a more comprehensive look at tumor growth for the staging of cancers, location of tumors, and the effectiveness of therapeutic agents and/or surgery. It also will enable earlier detection and more accurate diagnosis of cardiovascular and neurological diseases, and improve therapy and monitoring.
"In the future, I think PET/CT will be a first-line procedure in the management of patients with cancer," said
James W. Fletcher, MD, director of nuclear medicine and director of the Clinical PET Imaging Center at the IU School of Medicine.
PET imaging uses radiopharmaceutical tracers in the body that measures metabolic, biochemical and functional activity in living tissue. CT - more commonly called CAT scans - produces a series of images showing anatomical structure and abnormalities that do not normally show up on conventional X-rays.
PET or positron emission tomography has been available for clinical use since 1990 but wasn't routinely used for cancer management until it received initial Medicare coverage for lung cancer in January 1998. Its use for diagnosis, initial cancer staging and evaluation of response to therapy has expanded greatly since that time. It also is an effective tool for physicians wanting to see the viability of tissue in the heart and to study brain metabolism for tumors and diseases such as Alzheimers.
"PET's biggest limitation is poor spatial resolution," says
Gary Hutchins, Ph.D., director of Imaging Science and vice chairman of research in the Department of Radiology. "On the other hand," he adds, "CT images excel at showing spatial context. The dual modality has brought a new dimension, literally, to his research into the mechanisms of cancer growth."
"In certain common cancers, CT has been wrong in over half the instances where CT indicated the patient's cancer was operable," said Dr. Fletcher. "CT can often miss metastatic sites."
Combining the two technologies overcomes the limitations of either technology individually and gives physicians the closest thing to 20-20 vision available by letting them better identify and localize abnormalities.
"We now can find tumor sites not seen just through PET or CT alone," Dr. Fletcher says. PET/CT gives physicians a better look at disease sites to determine if surgery is an option or if the cancer has spread beyond the point where surgery is recommended.
The combined imaging also offers physicians an opportunity at the outset of chemotherapy to see if the drug is working. If not, the protocol can be changed avoiding a long, ineffective treatment regimen for cancer patients.
  
Clinical images shown above are from the PET-CT Scanner which combines PET and diagnostic CT technology to produce a biograph image and measurements, which records in exquisite detail life processes at the molecular level of tissues and internal organs from one noninvasive diagnostic procedure. It has improved diagnostic accuracy and patient management and is used clinically to detect diseases, state, plan treatment, and monitor therapy.
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