[The 4 hr-washout-functional picture: a quantitative visualization of 201Tl myocardial stress kinetics and the significance of paradoxical redistribution]

Abstract

Between March and August 1983, 62 patients with suspected coronary artery disease were investigated by both 201Tl myocardial scintigraphy and coronary angiography. Functional images of the 4 h-201Tl-washout were compared with conventional scintigrams of the stress and rest phases and with results of coronary angiography. Myocardial scintigraphy with 4 views was performed immediately after exercise and 3-4 h later. After interpolative background subtraction, 4 h-washout functional images were computed from each of the initial scintigrams and the corresponding delayed scintigrams. Using a special-coded colour table, the 4 h-washout could be read quantitatively from the functional image. The additional analysis of washout images increased the accuracy of myocardial 201Tl scintigraphy for the detection and localization of coronary stenoses from 42% to 69%. Sensitivity increased from 42% to 73%, definitivity from 50% to 79%. Ischemic regions appeared more obvious in the washout images, even to less experienced observers. In comparison with circumferential washout profiles the interpretation of washout images was easier because of more obvious anatomical localization. The phenomenon of "reverse redistribution" was found to be associated with a decreased 201Tl-washout in apparently "normal" regions, whereas in those regions with "reverse redistribution" the washout was normal or at least relatively high. In addition diffuse myocardial ischemia occurring in 3-vessel disease could be recognized in the 4 h-washout functional images.