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.
With the recent growth of cardiac PET imaging, the supply of isotopes is quickly moving towards capacity within the next 1-3 years. Annual demand for radioisotopes specific to cardiac PET imaging are expected to reach $35 million over the next few years and with continued growth estimated at 25-30% per year, thereafter.
The evolution to PET will further be accelerated by SPECT supply chain challenges in the near future. Cardiac SPECT will face significant pressure from a looming shortage in supply of molybdenum-99 (Mo-99), the radioactive imaging agent utilized in SPECT, because of the closure of one, potentially two, nuclear reactors scheduled for 2015-2016; these reactors produce 75% of the worlds radioisotope supply for SPECT imaging.
The U.S. market for SPECT and PET radiopharmaceuticals is large and rapidly growing. Sales reached $1.2 billion in 2010 and are expected to rise to $6 billion by 2018. As a result of new products and an anticipated increase in procedures, Bio-Tech Systems expects accelerating growth of PET radiopharmaceuticals (oncology and cardiac), resulting in $4.31 billion sales by 2018 vs. SPECT sales of $1.68 billion.
According to the Centers for Disease Control and Prevention, Coronary Artery Disease (CAD) accounts for:
• more than 385,000 U.S. deaths annually
• someone in the U.S. has a heart attack every 34 seconds
• someone dies in the U.S. from a heart disease-related event every 60 second
• CAD costs the U.S. $108.9 billion each year