| Objective: To evaluate the accuracy of coronary tomography angiography(CCTA)in diagnosis of coronary in-stent restenosis with using of catheterization coronary angiography as the standard of reference.Exploring the value and limitation of measuring and analyzing the CT density difference of the two sides of stents and the attenuation gradient distal of the stents in diagnosis of coronary stent stenosis and occlusion.Methods: 133 patients suspected with coronary in-stent restenosis and/or new coronary artery stenosis after stent implantation were underwent both CCTA and catheterization coronary angiography examination from October 2011 to January 2016.The interval time between CCTA and catheterization coronary angiography was 1~18(7.38 ± 4.97)days.There were 52 males and 18 females,and age was 36~87(65.5 ± 9.97)years old.All patients(203 coronary arteries)received percutaneous coronary artery(PCI)before CCTA examination 2 ~ 189(50.18 ± 37.29)months.CCTA using prospective-ECG triggered sequential scan mode for patients with ventricular premature beat and retrospective ECG-gated spiral scan mode for other patients.Acquisition parameters were as follows: 280 ms gantry rotation time,2×64×0.6 mm detector collimation,2×128×0.6 mm Z-flying focal spot technique.The tube voltage was set as 120 k V and the tube current was 330-420 m As every round.75 ms time resolution of reconstruction.Parameters for image reconstruction include time resolution of 75 ms,a slice thickness of 0.75 mm,increment of 0.7 mm.The field of view was 250~270mm.The matrix was512×512.Images were reconstructed with filtered back projection(FBP)and a medium soft convolution kernel(B26f).Contrast medium enhancement was achieved byinjecting 70~85 ml of iodinated contrast material and injected at 5.5~6 ml/s followed by30~50 ml of saline by using Ulrich high pressure injector.A test bolus was first injected and the region of interest was placed within the aorta arch to determine the required delayed time,which was defined as 6 s when the CT density of interest of the ascending aorta was over 100 HU.Selected the best cross-sectional images to assessment and analysis.Evaluating the accuracy of CCTA anatomical analysis in diagnosis of coronary stent stenosis and occlusion.203 coronary artery with stents were divided into three groups(stent patency?stent stenosis and stent occlusion)by the results of catheterization coronary angiography,then comparing the corrected coronary opacification(CCO)difference across stents and analyzing the attenuation gradient distal of the stents in the three groups.Results: Based on the results of catheterization coronary angiography,203 coronary arteries were divided into three groups,of all coronary arteries,116(57%)without stent restenosis,52(26%)with stent stenosis and 35(17%)with stent occlusion.Compared with the catheterization coronary angiography,the sensitivity,specificity,positive predictive value and negative predictive value of anatomical analysis with CCTA in diagnosing stent stenosis and occlusion was 85.06%?91.38%?88.10% and 89.08%.The sensitivity,specificity,positive predictive value and negative predictive value of anatomical analysis with CCTA in diagnosing stent occlusion was 77.14%?92.86%?69.23% and 95.12%.The CCO difference across stent with occlusion was 0.463±0.157,which was significant higher than stent with stenosis(0.216±0.051)and stent without stenosis(0.028±0.073)(p < 0.01).The CCO difference of stent with stenosis was significant higher than stent without stenosis(p<0.01).The sensitivity and specificity of CCO difference across stent stenosis cutoff ? 0.155 were 90.40% and 76.80%.The sensitivity and specificity of CCO difference across stent occlusion cutoff?0.333 were85.70% and 98.10%.20%(7/35)coronary arteries had reverse attenuation gradient and37.14%(13/35)coronary arteries had forward attenuation gradient in stent with occlusion(n=35).67.24%(78/116)coronary arteries had forward attenuation gradient in stent without restenosis(n=116).59.62%(31/52)coronary arteries had forward attenuation gradient in stent with stenosis(n=52).No reverse attenuation gradation signs were observed in both stent with stenosis and stent without restenosis.Conclusion:(1)CCO difference across stents elevated as stent restenosis severity increased,which can improve the accuracy of CT and be used as an important supplement of the anatomical analysis for diagnosing coronary stent restenosis.(2)It may be helpful by analyzing the reverse attenuation gradient distal to the stents,which had contribute to identify the stent occlusion from stent restenosis. |
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