Multiple Dose Reduction Techniques With Subtraction Coronary CT Angiography for Patients With High Calcification Scores.

Abstract

Purpose: To assess the effectiveness of various dose reduction strategies in subtraction coronary CT angiography (S-CCTA) for patients with elevated coronary artery calcification scores.

Methods: Fifty sequential patients, each possessing a calcification score of at least 400, were subjected to scans employing several dose reduction methods, such as narrowed acquisition windows, decreased tube voltage, diminished tube currents, isocentric scanning, and adaptive iterative dose reduction (AIDR). This study involved the execution of both subjective and objective evaluations to assess the image quality and diagnostic precision of contrast-enhanced CCTA (C-CCTA) and subtraction CCTA (S-CCTA). A quantitative analysis of coronary artery calcification was performed by measuring the circumferential extent of cross-sections, and patients were classified in accordance with the Coronary Artery Disease Reporting and Data System (CAD-RADS) guidelines. To assess the diagnostic accuracy of CCTA in relation to subtraction data, invasive coronary angiography (ICA) was utilized as the gold standard reference.

Results: The mean effective radiation dose recorded was 1.08±0.29 mSv. No notable disparities in image quality, either subjective or objective, were detected between C-CCTA and S-CCTA ( P >0.05); however, an exceptionally strong correlation (ICC=0.95, 0.94) was observed between the subjective assessments of the 2 modalities. Within 768 assessable segments, S-CCTA exhibited superior sensitivity (87.50% vs. 78.52%) and specificity (92.58% vs. 82.42%) compared with C-CCTA ( P <0.001). S-CCTA significantly enhanced diagnostic accuracy in severely calcified segments from 49.12% to 74.56% ( P <0.001), with notable improvements also in moderately (57.41% to 82.41%, P <0.001) and mildly calcified segments (65.56% to 85.56%, P =0.002).

Conclusion: Employing multiple dose reduction techniques markedly diminishes the radiation exposure in subtraction coronary CTA and improves the diagnostic accuracy in classifying calcified coronary stenoses.