Multi-organ functional imaging with thallium-201: a new noninvasive method for rapid assessment of vasoactive drugs.

A new method for rapid and noninvasive assessment of vasoactive drugs is described, using scintigraphic imaging with thallium-201 in anesthetized dogs. The scintigraphic images were processed to evaluate the effects of the vasoactive agents studied upon the biodistribution of thallium-201 in the whole body of dogs. The calculation of the functional parameter was based upon the comparison of the cell by cell increase of the tracor uptake following two different injections: the first in the basal state, the second after treatment with a vasoactive drug. Six drugs were tested and their effects evaluated in heart, liver, lungs, kidneys, and skeletal muscles. The most marked effects on myocardium were observed with dipyridamole and the ionophore grisorixin, two coronary vasodilators, which induced a strong increase in the TI-201 myocardial uptake (168.9 +/- 31.6% and 194.9 +/- 34.2% respectively). The results obtained in the other organs with all the drugs tested were in accord with their known hemodynamic properties, and so confirm the usefulness of this method.