Have your Medical Physicist and Cardiologists hammer out a stress/reinjection dose chart that will maintain the image quality that we all expect.Dose For stress imaging 4-5 m Ci is administered then a 1-2 m Ci injection is given 30 minutes prior to redistribution imaging, with a total dose not exceeding 7 m Ci.
What makes Tl-201 ideal for detecting reversible ischemia in cardiac muscle is the dynamic equilibrium of Tl-201 between the myocardium and vascular pool.
Thus, several hours after initial tracer administration the scintigraphic images depict an equilibrated pattern.
This is the basis of the “stress-redistribution” imaging strategy that has been used in the detection of CAD.
It remained popular even after 99m Technetium based tracers became available for single-day imaging protocols, viability studies, or in conjunction with 99m Tc tracers in ‘hybrid’ dual-isotope protocols.
It was common to do resting Thallium perfusion imaging, followed by 99m Tc-sestamibi gated SPECT stress imaging, combining the best characteristics of both radiopharmaceuticals.
This reversibility, whether after resting or exercise injection, is associated with the presence of viable myocardium.