Retrospectively ECG-gated Reconstructed Multislice Spiral CT Coronary Angiography And It's Clinical Application

Recently, with the rapid development of computer technology, using retrospectively ECG-gated reconstructed multislice spiral computed tomography (MSCT) coronary angiography to evaluate the coronary artery stenoses has become a hot point of clinic research. Due to the small diameter, irregular distribution and the rapid movement of coronary arteries, the image quality of reconstructed coronary artery with MSCT is still unsatisfied. In this study, we investigated the images reconstructed hi different R-R% phases with retrospectively ECG-gated multi-slice spiral CT coronary angiography, and tried to find an optimal retrospectively ECG-gated R-R% phase.. We also evaluated the clinical value of the images with various reconstruction methods in the detection of ≥50 % stenoses of coronary arteries.Twenty patients with suspicious coronary artery disease (CAD) were scanned by retrospectively ECG-gated MSCT with the parameters of 4 × 1.3mm cross-section,500-ms rotation and 0.375 pitch, during a single breath hold of 28-35 seconds. Transverse images were reconstructed at the starting points of 37.5%, 50.0%, 62.5% and 75.0% R-R phases respectively. Basing the transverse images, coronary arteries were reconstructed using different reconstructing methods, such as volume rendering (VR), multiplanar reconstruction (MPR) and virtual vascular endoscopy (WE). The qualities of images reconstructed with different R-R phases were graded. Nonparametric tests were employed to find the optimal reconstruction R-R phase for the coronary artery. We found that the left anterior descending artery was best estimated at 50.0% and 62.5% R-R phases; the left circumflex artery and the right coronary artery were also best valued at the R-R phase of 50.0% or 62.5%. There were no significant differences of the left main branches reconstructed with all four R-R phases (37.5%,50.0%, 62.5% and 75.0%). Reconstructed in optimal R-R phase, the transverse images, VR, MPR and WE images were compared with the results of selective coronary angiography(SCA). The transverse images were more valuable for detecting ≥50% stenoses of coronary arteries. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy were91.7%, 83.3%, 28.2%,99.3%and 83.9%. The accuracies of VR, MPR and WE were 79.4%, 71.7% and 61.7% respectively.Conclusions:1. Optimal R-R phase for retrospectively ECG-gated image reconstruction could be50.0% and 62.5% R-R phases..2. The transverse images are the basic images for detecting coronary artery stenoses, while VR can describe coronary artery stenoses visually, could be a valuable technique in clinical practice.3. The MSCT coronary angiography could be a screening test for patients before they receive SCA.