Processing of 201T1 serial images for the assessment of myocardial clearance and redistribution.

Regional activity changes over the myocardium after IV injection of 201T1 were assessed in 90 patients by applying a superposition algorithm for paired images. The kinetics were expressed as quotients C1/C2 of the initial divided by the delayed count rate within any myocardial segment. Regarding the total left ventricular myocardium, normal subjects showed count rate ratios (C30 min/C4 h) of 1.75 +/- 0.075 (SD, n = 19) when the nuclide was injected under submaximal (80% of maximum) exercise. In patients with triple-vessel disease (n=21) the corresponding values were 1.46 +/- 0.05, in single-vessel (n=14) disease the quotients averaged 1.62 +/- 0.12. Average quotients in poststenotic myocardial segments increased from 1.46 before to 1.73 following bypass surgery in cases of graft patency (n=8), while a decrease was observed in a patient with occlusion of the bypass graft. In small-vessel disease and in congestive cardiomyopathy, global values of 1.50 +/- 0.07 (n=7) and 1.53 +/- 0.12 (n=19) were obtained. The display of C1/C2 matrices provided typical patterns in uptake defects caused by ischemic heart disease and by congestive cardiomyopathy. The procedure described may provide diagnostic information in addition to conventional myocardial scintigraphy in triple-vessel disease, in patients with angina who fail to demonstrate hemodynamically significant coronary artery stenoses, and in patients with inhomogeneous T1-scintigrams.