Thallium-201 peripheral perfusion scans: feasibility of single-dose, single-day, rest and stress study

The distribution and redistribution kinetics of thallium-201 in the lower extremities were investigated to determine the relationships among the rest, stress, and delayed-stress perfusion studies. The distribution of perfusion when the tracer was administered at rest was compared with that when administered during stress, and the distribution 5--6 hr after the stress injection. The distribution was evaluated qualitatively by scanning and quantitatively by point counting. In nine of 10 subjects without peripheral vascular disease, the 5--6 poststress redistribution pattern was unchanged from the stress pattern and was different from the rest pattern. However, in all patients with peripheral vascular disease, the delayed poststress perfusion distribution had greater similarity to the rest pattern and was substantially different from that noted immediately after stress. Using the time frame of this study, the stress and delayed-stress 201Tl perfusion study of the lower extremities cannot be used to represent true rest perfusion. However, because of the similarity of the delayed-stress to the true rest distribution in abnormals, it may be clinically useful in defining rest and stress alterations.