The accuracy of 1-day dual-isotope myocardial SPECT in a population with high prevalence of coronary artery disease.

BACKGROUND: In order to evaluate the diagnostic efficacy of the 1-day separate acquisition dual-isotope single-photon emission computed tomography (SPECT) protocol, using 201Tl for the rest and 99mTc-tetrofosmin for the stress images, a consecutive series of patients with suspected or known coronary artery disease (CAD) was studied that also underwent coronary angiography. METHODS: The results of myocardial SPECT, using a semi-quantitative visual analysis, were acquired in 123 patients and compared with the results of coronary angiography. Sensitivity and specificity were calculated, using thresholds of > or = 50 and > or = 70% stenosis. As an alternative for specificity, the normalcy rate was determined in a separate group of 87 patients with a < 5% pre-test likelihood of CAD. RESULTS: The prevalence of CAD using > or =50 and > or = 70% stenosis was 88 and 78%, respectively. The sensitivity for detection of patients with > or = 50 and > or = 70% stenosis was 94 and 97%, respectively while specificity was 62 and 59%, respectively. The high rate of false positive perfusion defects resulting in a low specificity could be explained by specific clinical issues. However, the routine assessment with additional clinical and electrocardiographic data resulted in a correct interpretation of most of the false positive perfusion defects. The positive predictive value was 92 and 85% and the negative predictive value 46 and 77%, using thresholds of > or = 50 and > or = 70% stenosis, respectively. The normalcy rate was 91%. CONCLUSION: The one-day separate acquisition rest 201Tl/stress 99mTc-tetrofosmin SPECT protocol is an efficient procedure for myocardial perfusion scintigraphy with high sensitivity for detection of CAD. Specific clinical issues caused a low value for specificity. Therefore, clinical information and knowledge of the electrocardiogram is essential for a correct interpretation of SPECT images.

Incremental prognostic value of myocardial SPET with dual-isotope rest (201)Tl/stress (99m)Tc-tetrofosmin.

The incremental prognostic value of dual-isotope myocardial perfusion scintigraphy using technetium-99m tetrofosmin for the stress images was evaluated in 597 consecutive patients with known or suspected coronary artery disease. We used semi-quantitative visual analysis with a five-point scoring system and calculated the summed stress score, the summed rest score and the summed difference score. During the 2-year follow-up period, 46 "hard" cardiac events occurred: 16 cardiac deaths and 30 non-fatal myocardial infarctions. Kaplan-Meier analysis demonstrated a favourable prognosis for patients with normal scans as compared with patients with mildly to moderately or severely abnormal scans ( P<0.001). Multivariate analysis demonstrated incremental prognostic information for nuclear variables. A very low rate of hard cardiac events was observed in patients with a low summed stress score. Thus, nuclear variables provide incremental prognostic information and could be used to guide the management process with respect to whether or not to proceed with further invasive procedures.