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Comparative Study
. 2010 Nov 30;56(23):1914-21.
doi: 10.1016/j.jacc.2010.05.057.

Agreement of visual estimation of coronary artery calcium from low-dose CT attenuation correction scans in hybrid PET/CT and SPECT/CT with standard Agatston score

Andrew J Einstein  1 , Lynne L Johnson, Sabahat Bokhari, Jessica Son, Randall C Thompson, Timothy M Bateman, Sean W Hayes, Daniel S Berman
Affiliations
Comparative Study

Agreement of visual estimation of coronary artery calcium from low-dose CT attenuation correction scans in hybrid PET/CT and SPECT/CT with standard Agatston score

Andrew J Einstein et al. J Am Coll Cardiol. .

Abstract

Objectives: We sought to evaluate the accuracy and reproducibility of visual estimation of coronary artery calcium (CAC) from computed tomography attenuation correction (CTAC) scans performed for hybrid positron emission tomography (PET)/computed tomography (CT) and single-photon emission computed tomography (SPECT)/CT myocardial perfusion imaging (MPI).

Background: At the time of MPI, hybrid systems obtain a low-dose, non-electrocardiogram (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: A total of 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 6-level scale: classifying patients as estimated AS of 0, 1 to 9, 10 to 99, 100 to 300, 400 to 999, or ≥1,000. Agreement between visually estimated coronary artery calcium (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 nongated, 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 1 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 sex. Readers reported identical scores in 65% of cases and scores within 1 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.

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Figures

Figure 1
Figure 1. Example case (Columbia) comparing non-gated, non-breath-hold CT images obtained for attenuation correction (left) with standard ECG-gated, breath-hold calcium scoring images (right)
Agatston score is 2640, and was visually estimated to be ≥1000 by both readers.
Figure 2
Figure 2. Example case (Mid America Heart) comparing non-gated, breath-hold, very low tube current CT images obtained for attenuation correction (left) with standard ECG-gated, breath-hold calcium scoring images (right)
Agatston score is 367, and was visually estimated to be 100-399 by one reader and 400-999 by the other reader.
See this image and copyright information in PMC

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