Retrospectively electrocardiographically-gated reconstructed multi-slice spiral CT coronary angiography: optimal R-R phase and clinical application

Objective: To investigate the optimal R-R phase of retrospectively electrocardiographically (ECG)-gated image reconstruction for multi-slice spiral CT (MSCT) coronary reconstruction and it's clinical application. Methods: A total of 20 patients with known or suspected coronary artery disease (CAD) were detected with retrospectively ECG-gated MSCT (4 x 1.3 mm cross-section, 500-ms rotation, pitch 0.375) during a single breath hold. Tomographic source images were reconstructed at the starting points of 37.5%, 50.0%, 62.5%, and 75.0% R-R intervals, followed by volume rendering (VR) and virtual vascular endoscopy (VVE) for reconstruction of coronary artery. The quality of images reconstructed with different R-R phases was analyzed in terms of artifacts and visibility. Selective coronary angiography (SCA) was used for reference. Results: The left anterior descending artery, the left circumflex artery, and the right coronary artery were all best visualized at 50.0% and 62.5% R-R phases. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for the detection of ≥50% stenosis with the optimal R-R phase imagines of MSCT were 91.7%, 83.3%, 28.2%, 99.3%, and 83.9%, respectively. Conclusion: The optimal R-R phase of retrospectively ECG-gated reconstruction images can decrease the artifacts of cardiac motion and improve the reconstructive image quality of coronary arteries. With high sensitivity and negative predictive value, MSCT coronary reconstruction is considered as a good screening test before SCA