Preserved diagnostic performance of dual-source CT coronary angiography with reduced radiation exposure and cancer risk

Purpose: To evaluate the effects of standard and optimal electrocardiographic (ECG) pulsing on diagnostic performance, radiation dose, and cancer risk in symptomatic patients in a "real-world" clinical setting. Materials and Methods: The institutional review board approved the study, and all patients gave informed consent. Dual-source computed tomographic (CT) coronary angiography was performed in 436 symptomatic patients (301 men, 135 women; mean age, 61.6 years ± 10.6 [standard deviation]; age range, 23-89 years) referred for conventional coronary angiography. Standard and optimal ECG pulsing was performed in 327 and 109 patients, respectively. The diagnostic performance of dual-source CT coronary angiography for detection of significant stenosis (≥50 luminal diameter reduction), with quantitative coronary angiography as the reference standard, was reported as sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios. The mean effective radiation dose, additional fatal cancer risk, and age- and sex-specific cancer risks related to one CT coronary angiographic examination were determined from data averaged over the study population. Results: Mean effective doses with standard and optimal ECG pulsing were 14.2 mSv ± 3.2 and 10.7 mSv ± 3.6, respectively. Optimal ECG pulsing resulted in a 43% overall reduction in mean effective radiation dose and cancer risk compared with a nonpulsing protocol (18.8 mSv ± 3.5) and a 25% overall reduction in mean effective dose compared with the standard pulsing protocol. At patient-by-patient analysis, CT coronary angiography with standard ECG pulsing yielded sensitivity, specificity, and positive and negative predictive values of 100% (95% confidence interval [CI]: 99%, 100%), 85% (95% CI: 81%, 88%), 94% (95% CI: 91%, 96%), and 99% (95% CI: 98%, 100%), respectively, for detection of significant stenosis. Optimal ECG pulsing yielded similar results: Sensitivity, specificity, and positive and negative predictive values were 100% (95% CI: 100%, 100%), 88% (95% CI: 82%, 94%), 97% (95% CI: 93%, 100%), and 100%, respectively. Conclusion: Compared with a nonpulsing protocol, optimal ECG pulsing resulted in significant (P < .001) reductions in patient radiation dose and cancer risk (up to 55% reduction in patients with high heart rates) while preserving the diagnostic performance of dual-source CT coronary angiography.

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