Coronary artery stenoses: accuracy of 64-detector row CT angiography in segments with mild, moderate, or severe calcification--a subanalysis of the CORE-64 trial

Abstract

Purpose: To evaluate the influence of cross-sectional arc calcification on the diagnostic accuracy of computed tomography (CT) angiography compared with conventional coronary angiography for the detection of obstructive coronary artery disease (CAD).

Materials and methods: Institutional Review Board approval and written informed consent were obtained from all centers and participants for this HIPAA-compliant study. Overall, 4511 segments from 371 symptomatic patients (279 men, 92 women; median age, 61 years [interquartile range, 53-67 years]) with clinical suspicion of CAD from the CORE-64 multicenter study were included in the analysis. Two independent blinded observers evaluated the percentage of diameter stenosis and the circumferential extent of calcium (arc calcium). The accuracy of quantitative multidetector CT angiography to depict substantial (≥ 50%) stenoses was assessed by using quantitative coronary angiography (QCA). Cross-sectional arc calcium was rated on a segment level as follows: noncalcified or mild (< 90°), moderate (90°-180°), or severe (> 180°) calcification. Univariable and multivariable logistic regression, receiver operation characteristic curve, and clustering methods were used for statistical analyses.

Results: A total of 1099 segments had mild calcification, 503 had moderate calcification, 338 had severe calcification, and 2571 segments were noncalcified. Calcified segments were highly associated (P < .001) with disagreement between CTA and QCA in multivariable analysis after controlling for sex, age, heart rate, and image quality. The prevalence of CAD was 5.4% in noncalcified segments, 15.0% in mildly calcified segments, 27.0% in moderately calcified segments, and 43.0% in severely calcified segments. A significant difference was found in area under the receiver operating characteristic curves (noncalcified: 0.86, mildly calcified: 0.85, moderately calcified: 0.82, severely calcified: 0.81; P < .05).

Conclusion: In a symptomatic patient population, segment-based coronary artery calcification significantly decreased agreement between multidetector CT angiography and QCA to detect a coronary stenosis of at least 50%.

Figure 1a:

CT images show (a) noncalcified, (b) mildly calcified (cross-sectional arc calcium < 90°), (c) moderately calcified (cross-sectional arc calcium 90°–180°), and (d) severely calcified (cross-sectional arc calcium > 180°) segments. Segment calcification was measured by using the cross-sectional arc method (19).

Figure 1b:

CT images show (a) noncalcified, (b) mildly calcified (cross-sectional arc calcium < 90°), (c) moderately calcified (cross-sectional arc calcium 90°–180°), and (d) severely calcified (cross-sectional arc calcium > 180°) segments. Segment calcification was measured by using the cross-sectional arc method (19).

Figure 1c:

CT images show (a) noncalcified, (b) mildly calcified (cross-sectional arc calcium < 90°), (c) moderately calcified (cross-sectional arc calcium 90°–180°), and (d) severely calcified (cross-sectional arc calcium > 180°) segments. Segment calcification was measured by using the cross-sectional arc method (19).

Figure 1d:

CT images show (a) noncalcified, (b) mildly calcified (cross-sectional arc calcium < 90°), (c) moderately calcified (cross-sectional arc calcium 90°–180°), and (d) severely calcified (cross-sectional arc calcium > 180°) segments. Segment calcification was measured by using the cross-sectional arc method (19).

Figure 2:

Receiver operating characteristic curves and corresponding AUCs show diagnostic performance of 64–detector row CT angiography for identification of 50% or greater coronary stenoses at a segment level with QCA as the reference standard.

Figure 3:

Bar graph shows influence of segment calcification on the concordance, overestimation, and underestimation with multidetector CT angiography compared with CCA. Of the 2571 noncalcified segments, 2462 were concordant, 31 were false-positive, and 78 were false-negative. Of the 1099 mildly calcified segments, 977 were concordant, 57 were false-positive, and 65 were false-negative. Of the 503 moderately calcified segments, 402 were concordant, 60 were false-positive, and 41 were false-negative. Of the 338 severely calcified segments, 255 were concordant, 56 were false-positive, and 27 were false-negative.

Figure 4:

Bar graph shows influence of calcification on segment-level CT image quality. Of the 2571 noncalcified segments, 1208 were of good quality, 996 were of adequate quality, and 367 were of poor quality. Of the 1099 mildly calcified segments, 489 were of good quality, 436 were of adequate quality, and 174 were of poor quality. Of the 503 moderately calcified segments, 142 were of good quality, 247 were of adequate quality, and 114 were of poor quality. Of the 338 severely calcified segments, 25 were of good quality, 168 were of adequate quality, and 145 were of poor quality.