Molecular Nuclear Diagnostics enables physicians to accurately diagnose complex diseases, including cancer, cardiovascular and neurological disorders in their early stages, and improve follow-up. MND agents create functional images of the body allowing physicians to see the body’s internal workings and to analyze its chemical and biological processes. Patients are injected with a radiopharmaceutical tracer and imaged with PET (Positron Emission Tomography) or SPECT (Single Photon Emission Computed Tomography) cameras.
PET is a state-of-the-art technique in Molecular Nuclear Diagnostics. PET scans with fluorodeoxyglucose (FDG) have been a significant breakthrough in cancer treatment. They allow physicians to more accurately determine the precise stage of many tumors, localize unknown metastases and monitor therapeutic efficacy or the recurrence of the disease. In FDG PET, short-lived radioisotopes, like fluorine-18 (F-18) are attached to glucose (sugar) molecules to form FDG. Following injection into a patient, the drug is quickly absorbed by cancer or inflammatory disease cells, which are hyperactive and hungry for sugar. Once inside the cells, FDG releases positron particles that collide with the electrons in the body and produce energy in the form of opposite rays. These rays are detected by the PET camera, which produces a high quality metabolic image of the tumor or lesion.
The same principle applies to other radiopharmaceuticals that use different targeting molecules than glucose. Recently, additional radioisotopes, such as gallium Ga-68 have been attached to molecules targeting specific receptors in tumors, such as somatostatin analogues in neuroendocrine tumors. These PET products work in a similar manner to FDG, but target different types of tumors.
PET radiopharmaceuticals are complex and challenging to produce as they are generally short-lived, and once produced, must be transported and administered to patients in 10 hours or less, depending on the radioisotope used. Today PET is used in oncology, neurology, cardiology and infectious & inflammatory diseases.
SPECT has been used for over 50 years. In SPECT, a radioisotope, (usually technetium-99m, iodine-123, xenon-133, thallium-201, or fluorine-18) is attached to a chemical and injected into the patient’s blood stream, where it emits single gamma rays that are detected by the SPECT camera. SPECT differs from PET, in that the tracer stays in the blood stream, rather than being absorbed by surrounding tissues. The type of tracer used depends on what is being measured. This limits images to areas where blood flows. SPECT is used to diagnose a wide range of conditions within oncology, cardiology, neurology, and infectious diseases. Historically, there has been a lack of investment in SPECT radiopharmaceuticals, due to inferior picture quality when compared with PET. However, the next generation of SPECT cameras has mitigated this issue and produces similar image quality and accuracy to PET. SPECT products have longer shelf lives of up to several months, compared to ten or fewer hours for PET products, which means there are fewer logistical complexities.