Evaluation of subsecond gated helical CT for quantification of coronary artery calcium and comparison with electron beam CT.

OBJECTIVE Since its introduction early in the 1990s, helical CT has become the predominant technology for obtaining CT images for medical applications. Recent improvements in the temporal resolution of helical CT (subsecond) and the addition of retrospective cardiac gating are combined in this report evaluating cardiac-gated helical CT for quantifying coronary artery calcium. We compare total calcium scores determined on subsecond gated helical CT with the current reference for coronary calcium evaluation, electron beam CT. MATERIALS AND METHODS We compared total calcium scores obtained using a general purpose, unmodified helical CT scanner with scores obtained using electron beam CT in 36 individuals who were 68+/-11 years old (age range, 41-85 years). RESULTS Correlation coefficients ranged from 0.97 to 0.98 (Pearson's product moment) and from 0.95 to 0.96 (Spearman's rank order), depending on the coronary calcium scoring method used. Agreement in the classification of participants as "healthy" or "diseased" at threshold total calcium scores of 10, 100, 160, 200, 400, and 680 was, respectively, 94%, 97%, 89%, 92%, 94%, and 100% using the conventional electron beam CT scoring method and an equivalent method with helical CT. CONCLUSION A general purpose, current generation helical CT scanner equipped for retrospective cardiac gating can accurately quantify coronary calcium, and the results are highly correlated to scores obtained with electron beam CT. As an alternative method for measuring coronary calcium, gated subsecond cardiac helical CT offers greater availability and lower cost, thereby making population-based screening for coronary artery calcium more feasible.