Rubidium Rb-82

Rubidium-82m

Radioactive material

Atomic number: 37

In human studies, myocardial activity was noted within the first minute after peripheral intravenous injection of Rb-82. When areas of infarction or ischemia are present in the myocardium, they are visualized within 2-7 minutes after injection as photon-deficient, or “cold”, areas on the myocardial scan. In patients with reduced cardiac function, transit of the injected dose from the peripheral infusion site to the myocardium may be delayed Blood flow brings Rb-82 to all areas of the body during the first pass of circulation. Accordingly, visible uptake is also observed in other highly vascularized organs, such as the kidneys, liver, spleen and lungs.

Rb-82 is analogous to potassium ion (K+) in its biochemical behavior and is rapidly extracted by the myocardium proportional to the blood flow. Rb+ participates in the sodium-potassium (Na+/K+) ion exchange pumps that are present in cell membranes. The intracellular uptake of Rb-82 requires maintenance of ionic gradient across cell membranes. Rb-82 radioactivity is increased in viable myocardium reflecting intracellular retention, while the tracer is cleared rapidly from necrotic or infarcted tissue.