Coronary artery calcification measured at electron-beam CT: agreement in dual scan runs and change over time.

PURPOSE To use a recently described regression approach to evaluate agreement in the quantity of coronary artery calcification (CAC) with two consecutive acquisitions (dual scan runs) at electron-beam computed tomography (CT) in a quality-control program and to assess the change in CAC quantity over time in an individual. MATERIALS AND METHODS A total of 1,376 asymptomatic research participants, who were not selected because they were at high risk for coronary artery disease, were examined for the quantity of CAC with dual scan runs at electron-beam CT. With these data, 95% limits of agreement were established and used to evaluate differences between scan runs performed approximately 3.5 years apart in 81 participants. RESULTS The 95% limits of agreement depended on the mean quantity of CAC in the dual scan runs. Of the 81 participants whose examinations were approximately 3.5 years apart, 59 (73%) had no apparent change in CAC between the two examinations, 21 (26%) had large increases suggesting progression of CAC, and one (1%) had a large decrease suggesting regression of CAC. CONCLUSION The demonstrated method can be used to evaluate both agreement in dual scan runs and change in quantity of CAC over time.