Visual Assessment of Coronary Artery Calcium in Non-ECG Gated Chest CT: A Multicenter Study

Abstract

Purpose: We sought to evaluate the visual measurements of coronary artery calcium (CAC) in chest CT without ECG gating, and to compare their predictive abilities for obstructive coronary artery disease (CAD). Methods: We analyzed 163 subjects who underwent both coronary and chest CT examinations at 6 centers within 3 months. Agatston scores were calculated on standard ECG-gated scans and then classified into none (0), mild (1–99), moderate (100–400), and severe (>400) grades. Chest CT images were reconstructed with standard 5.0 mm axial slices. CAC in chest CT scans was measured using two methods: Weston score (sum of the assigned score of each vessel, range: 0–12) and number of slices showing CAC (Ca-slice#). Results: We found excellent inter-observer agreement in the estimates of the Weston score and Ca-slice# (R² = 0.913 and 0.955, respectively). When each of the two scores was divided into four levels, good agreement with the 4-grade Agatston score was observed (kappa value = 0.604 and 0.794, respectively). Of the 155 patients remaining after excluding non-diagnostic studies, obstructed CAD, defined as the presence of ≥70% stenosis on CT angiography, was found in 43 (27%). Receiver-operator characteristic curves of 4-grade hierarchies of Agatston score, Weston score, and Ca-slice# provided similar diagnostic powers to detect obstructed CAD (0.722, 0.706, and 0.718, respectively).Conclusion: The visual assessments of CAC detected by ECG non-gated chest CT scans were in good agreement with the ECG-gated Agatston score and also provided equivalent power to detect obstructive CAD. This study was registered at UMIN-CTR (identifier: UMIN000039178; registered date; Jan 16, 2020)