High-pitch Low-dose Chest Computed Tomography With Calcium-aware Reconstruction for Coronary Artery Calcium Scoring: Accuracy and Dose Reduction.

PURPOSE: To evaluate the accuracy, radiation dose, and clinical feasibility of a high-pitch low-dose chest CT (Sa36LDCT) scanning protocol with calcium-aware reconstruction for coronary artery calcium scoring (CAC). MATERIALS AND METHODS: In this prospective study, 90 patients underwent both standard CAC scanning (Qr36CACS, 120 kVp) and Sa36LDCT (70 to 120 kVp, high-pitch, ATVS). CAC scoring was quantified as Agatston score, calcium volume, and equivalent mass. Risk stratification was assessed using Agatston categories. Agreement between protocols was evaluated using intraclass correlation coefficients, Bland-Altman analysis, and weighted kappa. Subgroup analyses were performed according to heart rate (≤75 vs. >75 bpm). Radiation dose and subjective image quality were also compared. RESULTS: CAC metrics showed no significant difference between protocols, with excellent agreement (ICC = 0.983 to 0.996). Subgroup analysis revealed that heart rate did not significantly influence CAC quantification or risk classification, with Agatston score ICC values of 0.98 for ≤75 bpm and 0.99 for >75 bpm, demonstrating similar accuracy in both subgroups. Radiation dose reduction was consistently observed across both subgroups, with Sa36LDCT reducing effective radiation dose by 62% (0.74 vs. 0.28 mSv, P < 0.001), without compromising image quality. Risk stratification based on Agatston categories showed near-perfect consistency across heart rate subgroups (weighted k = 0.957). CONCLUSION: High-pitch Sa36LDCT provides accurate and reliable CAC scoring equivalent to standard CAC scoring, with substantial radiation dose reduction and preserved image quality. The protocol's robustness across heart rate subgroups demonstrates its potential as a safe and practical approach for combined pulmonary and cardiovascular screening, pending validation in larger, more diverse populations.