Quantitative exercise technetium-99m tetrofosmin myocardial tomography for the identification and localization of coronary artery disease

The aim of this study was to evaluate the accuracy of quantitative 1-day exercise-rest technetium-99m tetrofosmin tomography in the identification of patients with coronary artery disease (CAD) and in the detection of individual stenosed coronary vessels. Sixty-one patients with suspected CAD who underwent coronary angiography and 13 normal volunteers were studied. All patients were submitted to two i.v. injections of ^99mTc-tetrofosmin, one at peak exercise (370 MBq) and the other (1110 MBq) at rest 3 h after exercise (images 15-30 min after injection for both studies). All patients with CAD (≥ 50% luminal stenosis) (n = 50) had an abnormal ^99mTc-tetrofosmin tomogram. Only one patient without significant coronary narrowing showed abnormal findings. Overall sensitivity, specificity and diagnostic accuracy in the detection of individual stenosed vessels were 77%, 93% and 85%, respectively. Sensitivity and diagnostic accuracy in the identification of individuals stenosed coronary vessels were significantly higher (P <0.05) in patients with single-vessel disease (n = 21) than in those with multivessel disease (n = 29). Sensitivity, specificity and accuracy for detecting individual diseased vessels were similar in patients without previous myocardial infarction (n = 26) and in those with previous myocardial infarction (n = 35). In myocardial territories related to non-infarcted areas (n = 128), sensitivity and specificity in the detection of stenosed vessels were 70% and 95%, respectively. In infarcted areas (n = 55), sensitivity and specificity in the detection of stenosed vessels were 85% (P = NS vs non-infarcted areas) and 75% (P <0.05 vs non-infarcted areas), respectively. Finally, sensitivity was significantly lower (P <0.05) in vascular territories supplied by vessels with moderate stenosis (50%-75%) than in those supplied by vessels with severe stenosis (> 75%). The results of this study demonstrate that quantitative 1-day exercise-rest ^99mTc-tetrofosmin single-photon emission tomographic imaging is a suitable and accurate technique to identify patients with CAD and to detect individual stenosed coronary vessels.