Abstract 1771: Impact of Plaque Morphology and Vessel Opacification on Quantitative Coronary Angiography with 64-slice Computed Tomography
Objective: To assess the diagnostic accuracy of quantitative 64-slice computed tomography coronary angiography (CTCA) for the detection of significant coronary artery disease (CAD), and to confirm in vivo the impact of plaques morphology and vessel opacification on CTCA (as observed in vitro).
Methods: One hundred consecutive patients (42 women, 58 men; mean age 64.6 ± 9.4 years; age range 39 – 87 years) underwent CTCA and invasive quantitative coronary angiography (QCA). Each patient, each vessel and each vessel segment was considered as being significantly stenosed, when at least one stenosis was identified with a diameter reduction of ≥ 50%, comparing CTCA to QCA as the standard of reference. In CTCA stenosis severity was visually graded in 10% steps and evaluated separately for calcified and non-calcified coronary lesions using Pearson linear regression analysis and Mann-Whitney-U-test. Limits of agreement between QCA and CTCA were assessed according to Bland and Altman (BA). Contrast-to-noise ratios in the proximal coronary arteries were calculated to determine the influence of artery opacification on graded stenosis quantification by linear and quadratic correlation analysis.
Results: A total of 139 significant coronary artery stenoses were identified with QCA in 60/100 patients. On a per-segment analysis, overall sensitivity of CTCA was 75.5%, specificity was 96.6%, the positive predictive value was 72.9%, and the negative predictive value was 97.0%. Quantification of stenosis grading correlated moderately between QCA and CTCA (r=0.60; P<0.001), with an overestimation by CTCA of 5.5% (BA limits of agreement −29 to 39%). Differences of measured grades of stenosis were greater in the group with calcified lesions (p<0.05). The impact of coronary opacification on stenosis grading was non-significant.
Conclusion: The diagnostic accuracy of CTCA is high in patients with a high prevalence of CAD. The agreement for quantitative lesion severity assessment between CTCA and QCA was moderate for calcified but superior for non-calcified lesions. No impact of coronary opacification on stenosis grading was documented, most likely due to limitations inherent to CTCA (resolution) and QCA (planar projections).