The Study Of Technique And Clinical Application In Showing Coronary Angiography Using 64-detector Row CT

Part one:64-detector row CT coronary angiography:study on technique and image qualityObjective:To investigate technical aspects that influence the image quality at 64-detector row computed tomographic(64-MDCT) coronary angiography.Material and Methods:Coronary CT angiography was performed in 52 patients.Patients (mean age,62 years;nineteen women) were divided into three groups according to heart rates:group 1,＜70bpm;group 2,70 - 80bpm;group 3,≥80bpm.CT scans were obtained on a 64-MDCT scanner with a 64×0.625 mm collimation and 350-msec rotation time.A total of 15 data sets were reconstructed at 20-90%of the cardiac cycle in increments of 5%.Image quality of the coronary segments within three major coronary arteries was assessed by two radiologists independently with a four-step grading scale.Images assessed as grade 3 or 4 were considered to be of diagnostically acceptable quality.Results:A total of 517 segments were analyzed in 52 patients. Combining the scores for both reviewers,7 segments(1.4%) were judged unacceptable,428 segments(83%) were perfect.The middle segment of right coronary artery(RCA) had significant lower image quality and were more susceptible to the changes of heart rate.Best image quality was observed in group with a low heart rate for middiastolic reconstruction intervals(70- 80%of R-R interval) and in patients with a moderate or high heart rate for end-systolic or early-diastolic intervals (40～50%of R-R interval).Conclusion:64-MDCT has the potential to visualize 98.6%of cronary segments in patients with heart rates between 55 and 102 bpm.In patients with a heart rates＜70 bpm,the best results can be obtained with middiastolic intervals;in patients with a heart rates＞70bpm,the best image quality are achieved with end-systolic and early-diastolic intervals.Part two:The application of 64-MDCT in the diagnosis of CAD: Comparison with invasive techniquesObjective:The purpose of this study was to evaluate the potential clinical value of a 64-MDCT systems with that of invasive coronary angiography and intravascular ultrasound(IVUS)in the diagnosis of coronary artery disease.Material and Methods: Fifty-one consecutive patients(37man,14woman) aged 63 years±9 who were known or suspected of CAD underwent both coronary CT angiography and conventional coronary angiography.A CT system with acquisition of 64 slices per gantry rotation was used with a gantry rotation time of 350 milliseconds.Sensitivity,specificity,and diagnostic accuracy of 64-MDCT in the detection or exclusion of luminal stenosis greater than or equal to 50%were evaluated for each arterial segment,coronary vessel,and patient.In 10 patients,the results of CT were compare with IVUS in the detection of atherosclerotic plaque.Results:In 50 patients,MDCT was carried out without complications.One patient was excluded from the analysis due to the failure of scanning.Of 729 segment,707(97%) were judged evaluable by CT.QCA showed lesions with≥50%luminal narrowing in 8%(59/707) of the coronary segments. Sensitivity and specificity of 64-MDCT per segment were 92%and 96%.On a vessel-by-vessel and patients-by-patients basis,the sensitivity and specificity were 97%,88%and 100%,88%,respectively.Correlation of plaque areas and plaque burdens measured in MDCT and IVUS were relatively close(r=0.8,0.7).Conclusion: 64-MDCT is a reliable and accurate diagnostic tool in the detection of significant coronary stenosis with a sensitivity of 92%and a specificity of 96%.However,the potential of MDCT in detecting the component of plaques still was limited.Part three:Investigation of accuracy of 64-MDCT in the visualization of coronary stentObjective:To evaluate the accuracy of 64-MDCT correlation with that of conventional coronary angiography in the detection of in-stent lumen patency.Material and Methods:Fifteen consecutive patients(12man,3woman) with 21 stents delivered at least 6 months underwent both coronary CT angiography and conventional coronary angiography.Two independent blinded observers evaluated all stents for occlusion and restenosis(50%-99%luminal reduction).Conventional angiography was regarded as the standard of reference.Sensitivity,specificity,and diagnostic accuracy of 64-MDCT in the detection or exclusion of restenosis were evaluated.Results:Of 21 stents,18(86%) were considerd assessable.In the assessable segments,two restenoses and one occlusions were correctly detected by 64-MDCT,there was a sensitivity of 100%,a specificity of 87%and a accuracy of 89%,respectively.The K statistic demonstrated very good interobserver agreement( =0.72).Conclusion:64-MDCT allows noninvasive evaluation of stents,and may be a reliable tool in the follow-up of patients after coronary stent placement.Part four:The application and advantages of Multislice CT in the diagnosis of myocardial bridging.Objective:To investigate the ability of ECG-gated MSCT in the diagnosis of myocardial bridging.Materials and Methods:51 patients with suspected coronary artery disease underwent multi-detector row CT,conventional coronary angiography and intravascular ultrasonography(82 coronary arteries) as well.The sensitivity, specificity and accuracy of MSCT for the detection of myocardial bridging were determined.The interobserver agreement was also calculated by using Cohen's Kappa test.Results:A total of 26 tunneled arteries exclusively located near the middle segment of LAD were found by CA and IVUS,however two myocardial bridges confirmed by MSCT were missed.Compared with these invasive methods,MSCT correctly detected 25 of 26 myocardial bridges with a sensitivity of 88%,specificity of 96%and accuracy of 94%.Kappa for overall interobserver variation was 0.62. With the results of invasive and non-invasive methods combined as the standard of reference,the overall sensitivity,specificity,and accuracy of MSCT in detecting MB were 89%,91%,and 90%,respectively.Conclusions:As a non-invasive imaging modality,MSCT may be feasible and reliable in the detection of myocardial bridging.