Comparison of Tc-99m tetrofosmin and thallium-201 for evaluation of coronary artery disease

Tetrofosmin (Tf) is a new Tc-99m labeled myocardial imaging tracer with improved handling and kinetics. The aim of this study was to evaluate diagnostic accuracy of stress Tf SPECT in patients with suspected ischemic heart disease compared with thallium-201 SPECT. Sixty-three patients were studied with stress/rest Tf SPECT and 55 patients were studied with stress thallium SPECT. Twenty-four patients were studied by both methods and all had coronary angiography. Sensitivity and specificity to detect coronary artery disease were both quite sensitive; 94% and 60% for thallium vs. 94% and 71% for Tf (p=NS). The diagnostic accuracy for detecting significant stenosis (over AHA 75%) in the individual vessel lesion were similar for thallium and Tf: LAD 88% vs. 82%, LCX 61% vs. 81%, RCA 88% vs. 95%, but specificity and accuracy were higher for tetrofosmin than for thallium (p=NS): LAD specificity 77% vs. 88%, accuracy 82% vs. 86%, LCX specificity 61% vs. 81%, accuracy 84% vs. 90%, RCA specificity 68% vs. 80%, accuracy 75% vs. 86%. Visual assessment of the images suggested the Tf showed a smaller defect score in the anterior wall (p<0.02), septal wall (p<0.002), and infero-posterior wall (p<0.0001). These data indicate that Tf could reduce false positive results in these areas. Tf is a valuable myocardial tracer to detect coronary artery disease with a level of accuracy similar to that of thallium. Moreover, gated SPECT yields clinically useful additional information such as ejection fraction and wall motion. (author)