THE NON-CARDIAC DISTRIBUTION OF 99mTC-METHOXY-ISOBUTYL-ISONITRILE (SESTAMIBI) IN NORMAL BEAGLES

Technetium-99m methoxy-isobutyl-isonitrile (sestamibi) is a radiophartnaceutical used for the evaluation of myocardial perfusion. Increased uptake of sestamibi has also been documented in tumors. The objective of this study was to document the extracardiac biodistribution of ^99mTc sestamibi in the normal dog. Nine normal beagles were given 0.35 mCi/kg ^99mTc sestamibi intravenously, and 60 second images were made of the entire body at 1 hour post injection. A defined distribution pattern was recognized, with good visualization of the heart, liver, gallbladder, small intestine, kidneys, urinary bladder, popliteal lymph nodes, parotid salivary glands and zygomatic salivary glands. Splenic uptake was not seen.
Target to background ratios were calculated for all the regions listed, using background regions-of-interest with the smallest coefficient of variance for the denominator. The mean, range and standard deviation of these ratios are given.