Analyses Of Influencing Factors On Accuracy Of Coronary Artery Stenosis Evaluated By 256-slice ICT

Objective:To evaluate the accuracy of quantitative assessment of coronary stenosis by 256-slice iCT CCTA,and to explore the main factors affecting the accuracy of assessment.Methods:Data of 128 patients who underwent 256-slice iCT coronary angiography and CAG examination in the same period from February 2016 to January 2018 in the First Affiliated Hospital of Soochow university were collected.According to the 15-slice method formulated by the American Heart Association and according to the classification standard of stenosis degree by SCCT,the quantitative evaluation results of stenosis degree of each segment were statistically analyzed.CAG was used as the gold standard to reconstruct the inconsistent segments by CPR and to evaluate the inconsistent segments with coronary probe.To summarize the causes of non-conformity between SCCT and CAG,and to record the number of non-conformity segments caused by various causes.All data in this study were analyzed by SPSS 19.0 statistical software.Results:A total of 1631 segments were assessed.(1)CAG was used as the "gold standard" for the diagnosis of coronary stenosis.The degree of coronary stenosis was identical in 248 segments,not in 164 segments,false positive in 88 segments and false negative in 76 segments.The accuracy,sensitivity,specificity,PPV,NPV,(chi 2=1145.475,P<0.01)and Kappa were 94.36%,88.40%,96.06%,86.49%,96.67%,and 0.879(P<0.001)respectively.The diagnostic accuracy,sensitivity,specificity,PPV,NPV and Kappa were 95.89%,84.79%,97.60%,84.40%,97.66%and 0.774 respectively(P<0.001).(2)Ninety-eight non-conforming segments(40 false positive and 58 false negative)were corrected by secondary assessment,and 66 segments(48 over-estimated and 18 under-estimated)could not be corrected.The two assessment of coronary stenosis was significantly different(chi 2=43.17).(3)58 segments(35.37%)were found to be inaccurate due to severe calcification,accounting for 55.68%of false positive,34 segments were corrected;51 segments(overestimated 24 segments,underestimated 27 segments)were found to be inaccurate due to non-calcified plaque,accounting for 31.09%and 18 segments were corrected;23 segments were affected by improper location of measurement,all of which were corrected;the number of non-conforming segments caused by thin coronary artery,blurred or faulted vessels and MB-MCA were 23(14.02%),19(11.58%),7(4.27%)and 6(3.66%)respectively,which were corrected to some extent.Conclusion:The accuracy of 256-slice iCT angiography for assessing coronary stenosis is influenced by a variety of factors.Severe calcification is the most important factor affecting the accuracy of assessment,which can lead to overestimation;non-calcified plaque,improper selection of measurement sites,coronary branching and fine vessels are the more important factors affecting the accuracy of assessment,the first two factors Mainly caused by underestimation,is a controllable factor;MB-MCA and heart rate variability,arrhythmia,poor breath holding,etc.have relatively little impact on the stenosis assessment results.