Attenuation-corrected 99mTc-tetrofosmin single-photon emission computed tomography in the detection of viable myocardium:: Comparison with positron emission tomography using 18F-fluorodeoxyglucose

Objectives. The purpose of this study was to assess the efficacy of attenuation-corrected (AC) technetium-99m (Tc-99m)-tetrofosmin single-photon emission computed tomography (SPECT) in detecting viable myocardium compared to F-18-fluorodeoxyglucose (FDG) positron emission tomography (PET). Background. The role of Tc-99m-labeled perfusion tracers in the assessment of myocardial viability remains controversial. Attenuation artifacts affect the diagnostic accuracy of SPECT images. Methods. Twenty four patients with coronary artery disease (mean left ventricular ejection fraction 30%) underwent resting Tc-99m-tetrofosmin SPECT and FDG PET imaging, Both AC and non-attenuation-corrected (NC) SPECT images were generated, Results. Using a 50% threshold for viability by FDG PET, the percentage of concordant segments of viability between Tc-99m-tetrofosmin and FDG on the patient basis increased from 79.8% +/- 14.0% (mean +/- SD) on the NC images to 90.8% +/- 10.6% on the AC images (p = 0.002). The percentage of Tc-99m-tetrofosmin defect segments within PET-viable segments, an estimate for the degree of underestimation of viability, decreased from 19.8% +/- 15.2% on the NC images to 9.7% +/- 12.6% on the AC images (p = 0.01), Similar results were obtained when a 60% threshold was used to define viability by FDG PET. When the anterior-lateral and inferior septal regions were separately analyzed, the effect of attenuation correction was significant only in the inferior-septal region. Conclusions. The results indicate that AC Tc-99m-tetrofosmin SPECT improves the detection of viable myocardium mainly by decreasing the underestimation of viability particularly in the inferior septal region, although some underestimation/overestimation of viability may still occur even with attenuation correction. (C) 1998 by the American College of Cardiology.