Value of Visual and Quantitative Analysis of Thallium-201 Imaging in Patients with Diagnostic and Non-Diagnostic Exercise Electrocardiograms

Myocardial 201T1 imaging in conjunction with exercise stress testing has become an accepted technique for evaluating patients with known or suspected coronary artery disease. Especially in patients with an abnormal baseline repolarization on the electrocardiogram at rest, 20IT1 imaging has proven value. The aim of our study was (1) to evaluate the role of visual assessment and quantitative analysis of myocardial stress perfusion scintigraphy in 203 consecutive patients presenting for evaluation of possible coronary artery disease and (2) to evaluate the advantage of 201T1 myocardial imaging for the detection of coronary artery disease over exercise electrocardiography in patients with a normal electrocardiogram at rest and in patients with an abnormality of repolarization on the electrocardiogram at rest. Significant coronary artery disease (≥50% luminal stenosis) was present in 162 patients. The patients were divided into two groups: 121 patients with diagnostic exercise electrocardiograms (group 1) and 82 patients with non-diagnostic exercise electrocardiograms (group 2). The sensitivity of exercise electrocardiography in group 1 patients was not significantly different from that of visual analysis of myocardial perfusion scintigraphy (76 vs. 68%), but the sensitivity of the exercise electrocardiography was significantly higher than that of quantitative analysis of myocardial perfusion scintigraphy (76 vs. 63%; p = 0.0318). The sensitivity of visual analysis was not significantly different from that of quantitative analysis. The difference between the specificity of exercise electrocardiography and visual and quantitative analysis of myocardial perfusion scintigraphy was not significant (80 and 77% vs. 90%). The sensitivity of visual and quantitative analysis of myocardial perfusion scintigraphy in group 2 patients (both 90%) was significantly higher than that of visual and quantitative analysis of myocardial perfusion scintigraphy in group 1 patients (68 and 63%, respectively; p < 0.001). The specificity of visual and quantitative analysis of myocardial perfusion scintigraphy was not significantly different in group 1 patients (77 and 90%) when compared with the specificity of group 2 patients (both 82%). It is concluded that (1) visual and quantitative analysis of myocardial perfusion scintigraphy in detecting coronary artery disease offers no advantage for this purpose in patients with diagnostic exercise electrocardiograms when compared with exercise electrocardiography alone; (2) comparison of thallium scintigraphy (both visual analysis and quantitative analysis) in patients with diagnostic and non-diagnostic exercise electrocardiograms showed that sensitivity, specificity, and accuracy were higher in the group with the non-diagnostic exercise electrocardiograms; (3) the main advantage of exercise imaging with 201T1 is in patients with non-diagnostic exercise electrocardiograms.