Comparison of two different software systems for electron-beam CT-derived quantification of coronary calcification

OBJECTIVE. The growing interest in coronary calcium quantification by elect ron-beam CT (EBCT) has led to the development of various software systems f or the analysis of EBCT raw data, but it is unknown whether these software systems yield comparable results, METHODS. TWO sets of EBCT scans were obtained in 73 asymptomatic patients l ess than 15 minutes apart. Both scans of each patient were analyzed using t wo different software systems, the Mayo Clinic software and the AccuImage S coring System. The authors compared the calcium quantities yielded by the t wo different software systems, analyzed the interscan variability, and calc ulated the interobserver variability. Finally, they investigated the influe nce of the CT density factor inherent in the widely used Agatston score for the quantification of coronary calcium on reproducibility, RESULTS. The mean score determined by the Mayo Clinic software,vas 14% grea ter than that determined by the AccuImage system. The mean difference betwe en the two systems was 14% +/- 25%, and the median difference was 3%. The r elative mean and the median difference between the two scans of one patient were 15.3% and 6% determined by the AccuImage system and 17% and 6.5% dete rmined by the Mayo Clinic software. The interobserver reliability calculate d by the Mayo Clinic software was better than that of the AccuImage system, There was a trend for better reproducibility using calcium area rather tha n the Agatson score. CONCLUSIONS. Two different scoring systems do not necessarily yield the sam e result. Calcium quantities were systematically determined to be greater b y one system than the other, and there were significant differences with re gard to interobserver reliability. Hence, software should be tested with re gard to reproducibility data, and the interpretation of calcium quantities should acknowledge which type of software was used.