Interpretation between CAD-RADS & CAC-DRS CT angiography reporting systems to evaluate coronary artery disease severity

Abstract Background Noninvasive evaluation of coronary artery disease (CAD) by coronary-computed tomography angiography (CCTA) was progressively applied. One indicator of coronary atherosclerosis is the calcium score. However, little research has been done about how severe stenosis is related to it. Objective The main aim of this study is to assess whatever calcium deposition in coronary arteries, expressed in Coronary Artery Calcium—Data and Reporting System (CAC-DRS) is related to the degree of arterial lumen stenosis that expressed in Coronary Artery Disease—Reporting and Data System (CAD-RADS), the associations of these coronary scoring systems, and their validity to predict the extent of CAD. Patients and methods This was a cross-section observational study that involved 50 patients who were clinically suspected to have CAD and submitted for CCTA in the Radiology Department of Fayoum University Hospital. Two reviewers assessed the CCTA images and assigned the CAC-DRS and CAD-RADS categories independently for each case in a coronary segmentation manner. The invasive coronary angiography (ICA) was considered as a reference standard test which results interpreted blindly to evaluate the diagnostic quality in clinically indicated cases. The statistic results were built on the sensitivity and specificity, AUC, P - and KAPPA values for both coronary scoring systems. Results The diagnostic sensitivities of CCTA and ICA were 96.7% & 97.93%, correspondingly and diagnostic specificities were 83.3% for both modalities. The final results of comparison showed that there was no statistical significant difference in diagnostic accuracy between both modalities with p value = 0.63 and KAPPA = 0.762. The sensitivity and specificity values of CAC-DRS and CAD-RADS scoring systems for grading CAD upon coronary segmental basis were compared, and the ICA was used as a reference test, as following: CAC-DRS had an excellent sensitivity to grade CAD of 100% at all segmental sites, together with a good sensitivity of CAD-RADS of 92.9%. Both CAC-DRS and CAD-RADS had an excellent specificity of 100%. Both coronary scoring systems had a good PPV above 90.7% among the basal segments, and an excellent PPV of 100% at the rest of the middle and apical segments. CAD-RADS had an excellent NPV of 100%, compared to a poor NPV of CAC-DRS lower than 57.1% at all of the examined segments. The AUC value of CAC-DRS was relatively higher than that of CAD-RADS for the basal segments (75% vs. 71.4%), as well as at the middle segments (100% vs. 98.6%), but the AUC value of CAC-DRS was lower than that of CAD-RADS at the apical segments (96.6% vs. 100%). There was no statistical significant difference between both coronary scoring systems with high P- and KAPPA values at the basal segments (0.627 and 1), and the middle segments (0.951 and 1), yet smaller values at the apical segments (0.45 and 0.545), correspondingly. Conclusion This study proposes the following conclusions concerning coronary calcifications and the corresponding extent of CAD. First, coronary calcifications and stenotic degree are directly correlated upon segment-by-segment analysis, as well as whole-heart basis. Second, if there is a lack of correlation between calcifications and lumen stenosis, it would be probably due the effect of calcium-blooming, coronary spasm or vessel remodeling. Third, although coronary calcifications powerfully predict the existence of coronary atherosclerotic plaques, the absence of coronary calcifications does not exclude plaques presence. Finally, CAC-DRS and CAD-RADS are valued for promoting CCTA structural reports with great diagnostic accuracy and aids for decision-making.