Analysis of myocardial imaging data by mathematical kinetic model and two-successive imaging method by thallium-201...

The mathematical analysis of thallium-201 (Tl-201) kinetics showed that the uptake level reached a plateau in several minutes and the level was related to the blood level of T1-201 and the blood-myocardium partition coefficient. The regional perfusion rate was suggested to cause an enhanced uptake only in the early phase but not in the final equilibrium state. On the other hand an increase in the partition coefficient was shown to raise the level of equilibrium. Since the clinical imaging data are assessed in the equilibrium or near equilibrium state, a role of regional perfusion may be small for Tl-201 uptake unless it causes an ischemia. In the clinical data, the dependency of the uptake level upon the blood level of the isotope was confirmed especially when the blood-tissue transport was assumed to be constant. An alteration of uptake count was observed when heart rate was changed in the pacemaker-implanted patients. This change in Tl-201 uptake was suggested to be brought about by the change of the blood-tissue transport activity; hence the partition coefficient, not by the change in the perfusion rate, as suggested in the analysis of Tl-201 kinetics.