Coronary artery calcium severity grading on non-ECG-gated low-dose chest computed tomography: a multiple-observer study in a nationwide lung cancer screening registry.

• CAC severity grading methods on LDCT show moderate to substantial agreements between grading methods and observers. • Artery-based grading could be appropriate with substantial interobserver agreement and a mean evaluation time of 17.6 s. • Visual assessment is disadvantaged by high interobserver variability despite having the shortest evaluation time.