Reproducibility and accuracy of coronary calcium measurements with multi-detector row versus electron-beam CT

PURPOSE: To methodically evaluate the reproducibility and accuracy of coronary arterial calcification measurements by using spiral multi-detector row and electronbeam computed tomography (CT) with a beating heart phantom. MATERIALS AND METHODS: A phantom was built to mimic a beating heart with coronary arteries and calcified plaques. The simulated vessels moved in a pattern similar to that of a beating heart. The phantom operated at a variety of pulse rates (0-140 beats per minute). The phantom was repeatedly scanned in various positions by using various protocols with electron-beam and multi-detector row CT scanners to assess interexamination variability. Statistical analysis was performed to determine significant differences in interexamination variability for various acquisition protocols. RESULTS: Electrocardiographically (EKG) gated volume coverage with spiral multidetector row CT (2.5-mm collimation) and overlapping image reconstruction (1-mm increment) was found to significantly improve the reliability of coronary arterial calcium quantification, especially for small plaques (P < .05). Mean interexamination variability was reduced from 35% ± 6 (SD) (Agatston score, standard electron-beam CT) to 4% ± 2 (P < .05) (volumetric score, spiral EKG-gated multi-detector row CT). CONCLUSION: By coupling retrospective gating with nearly isotropic volumetric imaging data, spiral multi-detector row CT provides better input data for quantification of coronary arterial calcium volume. Multi-detector row CT allows precise and repeated measurement of coronary arterial calcification, with low interexamination variability.