Influence of Calcifications on Diagnostic Accuracy of Coronary CT Angiography Using Prospective ECG Triggering

OBJECTIVE. The purpose of this study was to investigate the diagnostic accuracy of dual-source CT coronary angiography with prospective ECG triggering compared with catheter angiography and to determine the influence of vessel wall calcifications. SUBJECTS AND METHODS. One hundred consecutive patients (42 women and 58 men; mean age, 65.8 +/- 6.5 years) with a sinus rhythm and heart rates < 70 beats per minute were included. Two independent, blinded readers classified coronary artery segments as being of diagnostic or nondiagnostic image quality and assessed each segment with diagnostic image quality for the presence of significant coronary stenoses. Nondiagnostic segments were excluded from analysis. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for all patients and for the subgroup of patients with a low or high calcium score (group A, median Agatston score < 316; group B, >= 316). Catheter angiography was used as the reference standard. Effective radiation dose values were calculated. RESULTS. In 89 of 100 patients (89%), 1,462 of 1,524 coronary segments (96%) were depicted with diagnostic image quality. The overall sensitivity, specificity, PPV, and NPV were 98%, 99%, 95%, and 100%, respectively. The rate of segments with nondiagnostic image quality was significantly higher (p < 0.001) in group B compared with group A. In group A, sensitivity, specificity, PPV, and NPV were 99%, 99%, 94%, and 100%, respectively, and in group B, 98%, 99%, 94%, and 99%, respectively, with no significant differences between the groups. The average effective radiation dose was 2.6 +/- 0.8 mSv (range, 1.2-4.4 mSv). CONCLUSION. Dual-source CT coronary angiography with use of prospective ECG triggering performs accurately in the assessment of coronary artery disease at low radiation doses. Diagnostic accuracy remains high despite the presence of heavy calcifications but is associated with an increased rate of nondiagnostic segments.