Unilateral kidney blood flow measurement using the 81Rb/81mKr ratio

A new method has been developed for the continuous quantification of kidney blood flow, utilizing the unique physical and biological properties of the radioactive tracer couple: rubidium-81/krypton-81m. After intravenous injection, 81Rb concentrates primarily in the kidneys, where it continuously generates the radioactive inert gas 81mKr. This ultrashort-lived isotope is continuously washed out from the tissue at a rate proportional to the blood flow. The radiation emitted from within the kidney is externally detected and analyzed to yield the 81Rb/81mKr ratio. 21 animal experiments have confirmed that this ratio is at any time an accurate measure of the kidney perfusion. The 81Rb/81mKr ratio method has proved to provide a non-invasive way to selectively quantify the blood flow in each kidney, to monitor perfusion changes and to image the distribution of blood flow in a functional scintigram.