Assessment of drugs by functional imaging of thallium-201 distribution in the dog.

The effect of drugs on thallium-201 biodistribution in the body has been studied in dogs using a new functional imaging method. The calculation is based upon the comparison of the activities of the two scintigraphic images obtained after two successive injections of thallium-201 separated by an interval of at least 10 min, during which some drug of interest can be administered. This imaging technique was applied in control dogs (n = 6) and in animals treated with dipyridamole (n = 7) or grisorixin (n = 7). As expected, these two vasoactive drugs increased mainly the myocardial uptake, whereas smaller variations were noted in the other organs studied: liver, kidney, lungs, and skeletal muscles. Thus this method should allow a rapid and reliable noninvasive assessment of cardiovascular drugs with thallium-201.