When the only gated sestamibi scan is the post-stress scan, global and regional LV function will not represent basal LV function in all patients with stress-induced ischemia.

Objectives We sought to evaluate the accuracy and reproducibility of visual estimation of coronary artery calcium (CAC) from CT attenuation correction (CTAC) scans performed for hybrid PET/CT and SPECT/CT myocardial perfusion imaging (MPI). Background At the time of MPI, hybrid systems obtain a low-dose, non-ECG-gated CT scan that is used to perform attenuation correction. Utility of this CTAC scan in estimating actual CAC as measured by Agatston score (AS) on standard ECG-gated scans has not been previously studied. Methods 492 patients from 3 centers receiving both MPI with CTAC and a standard CAC scan were studied. At each site, experienced readers blinded to AS reviewed CTAC images, visually estimating CAC on a six-level scale: classifying patients as estimated AS of 0, 1-9, 10-99, 100-300, 400-999, or ≥1000. Agreement between visually-estimated CAC (VECAC) on CTAC and AS, measured standardly and converted to the same scale, was evaluated, as was inter-reader agreement. Results Although CTAC images are low-dose and non-gated, a high degree of association was observed between VECAC and AS, with 63% of VECACs in the same category as the AS category and 93% within one category. Weighted kappa was 0.89 (95% confidence interval 0.88 to 0.91, p<0.0001). High weighted kappa statistics were observed for each site, scanner type, and gender. Readers reported identical scores in 65% of cases and scores within one category in 93%. Conclusions CAC can be visually assessed from low-dose CTAC scans with high agreement with AS. CTAC scans should be routinely assessed for VECAC.