PET - Positron Emission Tomography

PET technology is an advanced imaging technique, which permits the measurement of the biological processes of organs and tissues, as well as producing anatomical and structural images. Other advanced imaging techniques, such as magnetic resonance imaging and computed tomography, produce anatomical and structural images, but do not image or measure biological processes. The ability to measure biological abnormalities in tissues and organs allows physicians to detect disease at an early stage, and provides information, which would otherwise be unavailable, to diagnose and treat disease. The Company believes that PET technology can lower the total cost of diagnosing and tracing certain diseases by providing a means for early diagnosis and reducing expensive, invasive or unnecessary procedures, such as angiograms or biopsies which, in addition to being costly and painful, may not be necessary or appropriate.

These paired gamma events are detected by the PET as coincidence events. The source of the photons is determined and is reconstructed into a color image of the scanned organ utilizing proprietary computer software. Since certain functional processes, such as blood flow, metabolism or other biochemical processes, determine the concentration of the radiopharmaceutical throughout the body, the intensity or color at each point in the PET image directly maps the vitality of the respective function at that point within an organ.

A PET scan allows a physician to examine diseases of the heart, brain, and other organs and cancer. PET captures powerful images of the human body's function and reveals information on health and disease. Because disease is a biological process, and PET is molecular biological imaging examination, PET can detect and stage most cancers, often before they are evident through other tests. PET can also give physician’s important early information about heart disease and many neurological disorders, like Alzheimer's and Parkinson’s disease.

In cardiology, PET imaging is an accurate, non-invasive method of diagnosing or assessing the severity of coronary artery disease. Unlike other imaging technologies, PET technology allows a physician to determine whether blood flow to the heart muscle is normal, thereby identifying narrowed coronary arteries, and whether damaged heart muscle is viable and may benefit from treatment such as bypass surgery or angioplasty. In addition, dynamic and gated imaging can display and measure the ejection fraction and wall motion of the heart.

In neurology, PET imaging is now being used as a surgical planning tool to locate the source of epileptic disturbances in patients with uncontrollable seizures. In other neurological applications, PET is used in the diagnosis of dementia, Alzheimer’s disease, Pick’s disease and Parkinson’s disease, and in the evaluation of stroke severity.

In oncology, PET imaging has historically been used to measure the metabolism of tumor masses after surgery or chemotherapy. Clinical experience has shown that PET is more accurate than CT scans or MRI in determining the effectiveness of chemotherapy and radiotherapy in the treatment of cancer. PET scans are becoming commonly used to assess suspected breast cancer and whether the lymph system has become involved. Whole body PET scans are now routinely performed to survey the body for cancer. This application enables oncologists to see the total picture of all metastases in a patient, thereby allowing them to properly tailor the course of treatment.

(1) Source: The Journal of Nuclear Medicine Supplement, Volume 42, Number 5, May 2001 and UCLA

The radiopharmaceuticals employed in PET imaging are used by organs in their natural processes, such as blood flow and metabolism, without affecting their normal function, and quickly dissipate from the body. Radiopharmaceuticals used in PET procedures expose patients to a certain amount of radiation, which is measured in units of milliRads. Exposure to radiation can cause damage to living tissue, and the greater the radiation exposure, the greater the potential for damage. Certain PET procedures expose a patient to less radiation than would be associated with other imaging technologies. A PET cardiac scan, using the radiopharmaceutical Rubidium-82, results in exposure of approximately 96 milliRads, while a neurological PET scan using 18-FDG, results in exposure of approximately 390 milliRads. In contrast, a typical chest X-ray results in exposure of approximately 150 milliRads and a CT scan results in exposure of approximately 500 to 4,000 milliRads, depending on the procedure.

Radiopharmaceuticals used in PET technology can be created using many natural substances including carbon, oxygen, nitrogen and fluorine. The PET procedure to be performed determines the type of radiopharmaceutical used. Radiopharmaceuticals are made ready for use at a clinic, hospital, or commercial nuclear pharmacy by either a cyclotron or generator. Cyclotrons require an initial capital investment of up to $2 million, an additional capital investment for site preparation, and significant annual operating expenses. Generators require an initial capital investment of approximately $60,000, no additional capital investment for site preparation, and monthly operating expenses of approximately $30,000. As a result, clinics or hospitals intending to focus on certain cardiac PET applications can avoid the significant capital and operating expenses associated with a cyclotron.