In nuclear medicine procedures, radioisotopes are administered to a patient via direct injection in the form of a pure radioisotope or radioisotope compound where the radioisotope is attached to a drug compound. Radiopharmaceuticals are formulated to concentrate temporarily in a specific part of the body to be studied. The radiation signals emitted at the site of the temporary radioisotope concentration form a diagnostic image of the body part or organ. In contrast to other diagnostic imaging modalities, radiopharmaceuticals allow nuclear medicine to image, in real-time, the extent of a disease-process in the body, based on the cellular function and physiology (blood flow, organ function, metabolic activity and biochemical activity), rather than relying solely on physical changes in the tissue anatomy as revealed during CT scans. This diversity in application often enables nuclear medicine procedures to identify medical problems at an earlier stage than other diagnostic tests.
Isotopes are variants of chemical elements. While all isotopes of a given element share the same number of protons, each isotope differs from the others in its number of neutrons. There are two types of isotope configurations, stable and radioactive. Stable isotopes emit no radiation whereas radioactive isotopes emit radiation. A radioactive isotope is in an undesired state of instability and undergoes radioactive decay as it seeks a more stable configuration in its nucleus. Strontium-82 is used exclusively to manufacture rubidium-82 generators. The generator system makes rubidium-82; the most convenient Positron Emission Tomography (PET) agent in myocardial perfusion imaging.
Rubidium-82 chloride is used to produce an Rb-82 injection for intravenous administration. An Rb-82 injection is indicated for Positron Emission Tomography (PET) imaging of the myocardium under rest or pharmacologic stress conditions to evaluate regional myocardial perfusion in adult patients with suspected or existing coronary artery disease. It is rapidly taken up by heart muscle cells, and therefore can be used to identify regions of heart muscle that are receiving poor blood flow in a technique called PET perfusion imaging. The half-life of the rubidium 82 is only 1.27 minutes.
The evolution to PET will further be accelerated by SPECT supply chain challenges. Cardiac SPECT will face significant pressure from a looming shortage in the supply of molybdenum-99 (Mo-99), the radioactive imaging agent utilized in SPECT, because of the closure of nuclear reactors; these reactors produced 75% of the worlds radioisotope supply for SPECT imaging.