Segmental analysis of Ti-201 stress myocardial scintigraphy

Thallium-201 scintigraphy of the exercised myocardium was performed in 70 male patients admitted for coronary arteriography and left-ventricular angiography. Left ventricular scintigrams were collected in left lateral, left anterior oblique (65 degrees, 45 degrees, and 25 degrees), and anterior views, and the images were divided into eight segments: apical, anteroseptal, anterior, antero-lateral, posterolateral, posterior, inferior, and posteroseptal. A correlative study between segmental hypoperfusion on scintigram and coronary-artery stenosis visualized by contrast artriorgraphy allowed selection of specific segments for each main coronary artery. Hypoactivity in the apical and posterior segments did not appear reliable. Using selected segments, we were able to identify LAD disease in 84%, LCx disease in 49%, and RCA disease in 79% of documented significant stenosis, with specificity of 95%, 89%, and 88%, respectively. Coronary-artery disease could be detected in 95% of patients having more than 50% coronary-artery stenosis, with 93% specificity. In most cases, patients with two-vessels disease and three-vessel disease could not be distinguished from each other. Multiple-vessel disease suggested by segmental analysis of myocardial scinitgrams after exercise was confirmed artriographically in 88% of the patients, but 52% with scintigrams suggesting signle-vessel disease had, in fact, multiple-vessel disease.