Tc-99M-Sestamibi SPECT is a useful technique for viability detection - Results of a comparison with NH3/FDG PET

Objective - Assessment of myocardial viability by Tc-99m-Sestamibi Single P hoton Emission Computerized Tomography (SPECT) has been suggested as a more readily available and cheaper alternative to Positron Emission Tomography (PET) with N-13-ammonia (NH3) and F-18-fluoro-deoxy-glucose (FDG). We hypot hesized that a semiquantitative evaluation by SPECT could delineate myocard ial viability with an acceptable concordance to PET. Design - Fifty patients (age 57 +/- 7 years; ejection fraction 28 +/- 8%), with ischemic cardiomyopathy, underwent SPECT and PET imaging in random ord er. Viability by SPECT was defined as a defect size < 50% of the segment ar ea, or a defect representing greater than or equal to 50% of the segment bu t with a mean activity 50% of peak activity. PET viability was defined as a perfusion score >2 and FDG score <2 (five-point scale, 0 = normal, 4 = abs ent activity). Results - By segmental comparison to PET, SPECT yielded a sensitivity and s pecificity of 87% and 82% for detection of viable myocardium. The positive and negative predictive values were 96% and 58%. respectively. Conclusion - In patients with severe ischemic cardiomyopathy Tc-99m-Sestami bi SPECT can delineate viable myocardium with an acceptable segmental conco rdance to NH3/FDG PET.