The Technique And Clinical Applications Of Coronary Angiography With Multi-slice Spiral Computed Tomography

Objective: To investigate the optimal scan parameters and reconstruction methods and to demonstrate the possibilities and limitation of multi-slice spiral CT for contrast enhanced investigation of the coronary arteries.Methods: 52 patients were studied with multi-slice spiral CT(retrospectively ECG-gating; 0.5s rotation; cardiac segment or burst reconstruction algorithm; intravenous contrast agent). Volume data set of the heart reconstructed at 0%-90% window of the cardiac cycle in increments of 10% were analyzed with maximum intensity projection, curved planer reconstruction and volume rendering mode on a 3D imaging workstation. The relationships between heart rate, trigger delay and image quality were analyzed. In 32 patients with known or suspected coronary atherosclerotic heart disease, CT was compared with quantitative coronary angjography which served as the gold standard. The diagnostic accuracy of MSCT angiography was expressed as sensitivity, specificity and positive and negative predictive value.Results: (1) In 52 patients, 5 coronary bypass patients were all assessable. 3 82(84.14%)of the 454 coronary artery segments with a luminal diameter>2.0mm of the remaining 47 patients were considered assessable with MSCT angiography. The major causes were coronary motion artifacts(52 of 72 segments, 72.22%), most frequently in the middle segment of the right coronary artery and the distal segment of the left circumflex artery(30.77%). (2) In the 454 coronary artery segments, 318(70.04%) were best visualized at 70% imaging reconstructionwindow of the cardiac cycle, the optimal window of imaging reconstruction for the 17(3.74%), 102(22.47%), 7(1.54%) and 10(2.20%) coronary artery segments was at 30%, 40%, 50% and 80%, respectively. Left coronary arteries were best visualized at 70% image reconstruction window of the cardiac cycle and right coronary arteries at 70% and 40% image reconstruction window. (3) When using Snapshot Segment reconstruction algorithm, the coronary arteries of patients with heart rate less than 65BPM were better visualized than those of patients with more than 65 BPM(P<0.05). (4) According to patients with heart rate more than 65 BPM, the coronary arteries of MSCT were better visualized when using Snapshot Burst or Burst plus reconstruction algorithm than using Snapshot Segment reconstruction algorithm (P<0.05). (5) 19 of 24 significant stenoses (>50% lumen diameter narrowing in angiography) and occlusions were correctly diagnosed. The sensitivity, specificity, positive and negative predictive value of was 79.17%,97.11%,86.36% and 95.28%, respectively. (6) 4 implanted stents of coronary artery were all assessable, including three stent patency and one stent lesion been detected. 11 segments of bypass grafts were all assessable and two graft lesions were detected. Conclusion: (1) This cardiac imaging method was simple, reliable, noninvasive, low risk, comfortable, and nonexpensive. (2) There are several causes of unassessable imaging. Controling heart rate, correcting arrhythmia, sufficiently breathholding, suitable reconstruction algorithm, setting rational dose and injecting velocity of constract angnet and scan delay time and optimization of imaging reconstruction window are all important to obtain the best quality of MSCT imaging of coronary artery. (3) MSCT allows non-invasive imaging of coronary artery stenoses and has the potential to rule out CAD, permitting the evaluation of pre- and post-operative cardiovascular situation, coronary artery calcification screening and so on.