Rubidium-82

A vial of injectable Rb-82 and the generator.

Rubidium-82 (⁸²Rb) is a radioactive isotope of Rubidium. ⁸²Rb is widely used in myocardial perfusion imaging. This isotope undergoes rapid uptake by myocardiocytes, which makes it a valuable tool for identifying myocardial ischemia in Positron Emission Tomography (PET) imaging. ⁸²Rb is used in the pharmaceutical industry and is marketed under the trade name CardioGen-82.

In 1953 it was discovered that Rubidium carried a biological activity that was comparable to potassium. In 1959, preclinical trials showed in dogs that myocardial uptake of this radionuclide was directly proportional to myocardial blood flow. In 1979, Yano et al. compared several ion-exchange columns to be used in an automated ⁸²Sr/⁸²Rb generator for clinical testing. Around 1980, pre-clinical trials began using ⁸²Rb in PET. In 1982, Selwyn et al. examined the relation between myocardial perfusion and rubidium-82 uptake during acute ischemia in six dogs after coronary stenosis and in five volunteers and five patients with coronary artery disease. Myocardial tomograms, recorded at rest and after exercise in the volunteers showed homogeneous uptake in reproducible and repeatable scans. Rubidium-82 isotope has shown considerable accuracy comparable to that of ^99mTc-SPECT. In 1989, the FDA approved Bracco Diagnostics' ⁸²Rb/⁸²Sr generator for commercial use in the U.S. With increased ⁸²Sr production capabilities the use of ⁸²Rb has increased over the last 10 years.

The production of Rubidium-82 comes from the parent nucleus, Strontium-82.The ⁸²Sr/⁸²Rb generator is named CardioGen-82. The generator contains accelerator produced ⁸²Sr adsorbed on stannic oxide in a lead-shielded column and provides a means for obtaining sterile nonpyrogenic solutions of RbCl(Halide salt form capable of injection). The amount (millicuries) of Rb-82 obtained in each elution will depend on the potency of the generator. When eluted at a rate of 50 mL/minute, each generator eluate at the end of elution should not contain more than 0.02 microcurie of strontium Sr-82 and not more than 0.2 microcurie of strontium Sr-85 per millicurie of rubidium chloride Rb 82 injection, and not more than 1 microgram of tin per mL of eluate.

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