Coronary Artery Calcium Scoring on Low-dose Prospective Electrocardiographically-triggered 64-Slice CT

Rationale and Objectives. The purpose of this prospective study was to assess image noise and variability in repeated coronary artery calcium (CAC) scoring on low-dose prospective electrocardiographically-triggered 64-slice multidetector computed tomography. Materials and Methods. Patients (n = 115) suspected of having coronary artery disease were scanned twice, using a tube current of 10 X body mass index mA. The standard deviation (SD) of the Computed tomographic value in the ascending aorta and (mean + 2 X SD) were obtained. Repeated CAC scores (Agatston, Volume, and mass) were measured by two observers, and the interscan and interobserver variability were determined. Results. The mean tube current used was 246 +/- 36 mA. The mean tube current-time product and mean estimated effective dose were 57 +/- 8 mA and 0.9 +/- 0.2 mSv, respectively. The SD and (mean + 2 X SD) Computed tomographic values in the ascending aorta were 16 +/- 3 and 75 +/- 10 Hounsfield units, respectively. Repeated CAC scores were correlated (r(2) = 0.995-0.998). The interscan variability for observer I and observer 2, respectively, were 13% and 13% for Agatston score, 12% and 11% for volume, and 11% and 11% for mass. The interobserver variability for scan I and scan 2, respectively, were 3% and 3% for Agatston score, 5% and 3% for volume, and 3% and 3% for mass. Conclusion. Low-dose prospective electrocardiographically-triggered 64-slice multidetector computed tomography shows low interscan and interobserver variability on CAC scoring while maintaining low image noise.