| Objective: 1.To assess the clinical value of low-dose coronary artery CTA using 256-slice MSCT with Iterative Model Reconstruction.2.To explore the diagnostic accuracy of low-dose 256-slice MSCT with Iterative Model Reconstruction in the diagnosis of coronary heart disease.Methods: 1.Patients: We collected 62 subjects(35 males and 27 females,aged from 41 to 82 years,average age:62 ± 9 years)who suspected or diagnosed with coronary heart disease in the Second Hospital of Dalian Medical University from March 2016 to December 2016.The inclusion criteria were a body mass index(BMI)of 20-25kg/m2.All the cases were divided into group A(80KV)and group B(100KV)with each group 31 cases.2.Scanners and parameters: All CCTA procedures were performed on a 256-slice MSCT(Brilliance iCT,Philips).Scan parameters: tube voltage 80KV(A group)and 100KV(B group);tube current was set to automatic milliamp regulation,collimator width of 128 × 0.625 mm,layer thickness 0.90 mm,layer spacing 0.45 mm,pitch 0.18,field of view(FOV)242 mm × 242 mm,matrix 512 × 512.Coronary angiography(CAG)was performed with Philips INTEGRIS. 3.Radiation dose analysis: Computed tomographic dose index volumes(CTDIvol)and dose length product(DLP)of two groups were recorded and the effective dose(ED)was calculated.4.Image quality assessment: The original data of two groups were reconstructed by Iterative Model Reconstruction(IMR),iDose4 in Hybrid Iterative Reconstruction(HIR),and Filtering Back-Projection(FBP)algorithm respectively.The mean CT value and background noise value(SD)of the coronary arteries were measured.CT values of pericardial fat were measured and the contrast noise ratio(CNR)was calculated.Two cardiovascular radiologists evaluated the subjective image quality scores of two groups with IMR,iDose4 and FBP respectively which included subjective image noise,vascular sharpness,streak artifacts,and overall image quality.The image quality of each segment of coronary artery was evaluated in group A(80KV)with IMR,iDose4 reconstruction and group B(100KV)with IMR.5.Evaluation of vascular stenosis: The degree of vascular stenosis was measured in 80 KV coronary CTA with IMR algorithm and coronary angiography respectively.6.Statistical analysis: The clinical data of the two groups using independent samples t test and chi-square test.Two groups of CT volume dose index(CTDIvol),dose length product(DLP)and effective radiation dose(ED)were compared using independent sample t test.The objective evaluation indexes of IMR,iDose4 and FBP in the two groups were compared by one-way ANOVA.The objective evaluation index of IMR between the two groups was compared with the independent sample t test.The subjective evaluation of IMR,iDose4 and FBP images in the two groups was compared using the Friedman test.The Mann-Whitney U test was used to compare the subjective evaluation of IMR between the two groups.The image quality score of each segment of the coronary arteries was compared between IMR and iDose4 in the 80 KV group using the Wilcoxon test.The Mann-Whitney U test was used in the IMR of the 80 KV group and 100 KV group. Differences of p<0.05 were considered statistically significant.Kappa test was used to test the consistency of CTA using the IMR technique with 80 KV tube voltage and CAG in the diagnosis of coronary stenosis.Results: 1.Radiation dose: Compared with group 100 KV,the radiation dose of group 80 KV decreased by 43.8%.2.Objective analysis of image quality: The SD and CNR of the IMR algorithm in both groups were significantly higher than those of the iDose4 algorithm and the FBP algorithm,the difference was statistically significant(p<0.001);The CT value of the IMR algorithm in the left anterior descending coronary artery(LAD)of the 100 KV group was significantly higher than that of the iDose4 and FBP algorithms(p<0.001),and the others CT values of the two groups used the three reconstructed algorithm were not statistically different(p>0.05).The CT value with IMR algorithm of each segment in the 80 KV group was significantly higher than that in the 100 KV group.The SD of the Proximal and middle segment of the 80 KV group was higher than that of the 100 KV group but there was no significant difference between the two groups of distal coronary arteries.The CNR of the aorta in the 100 KV group was higher than that in the 80 KV group(p<0.05),and the CNR of others coronary each segment was no significant difference(p>0.05)between the two groups.3.Subjective analysis of image quality: The subjective image quality scores of the IMR algorithm in both groups were significantly higher than those of the iDose4 algorithm and the FBP algorithm,the difference was statistically significant(p <0.001).The subjective image noise of the 100 KV group was less than 80 KV group(p<0.05)with the IMR algorithm.There was no significant difference between the two groups with IMR algorithm in vascular sharpness,streak artifacts and overall image quality score.The image quality score of each segments used the IMR algorithm in the 80 KV group was significantly higher than that in the iDose4 algorithm(p<0.05),and there was no significant difference compared with the IMR algorithm in the 100 KV group.4.Evaluation of coronary artery stenosis: The Kappa value in diagnosis of vascular stenosis rate between 80 KV tube voltage combined with IMR algorithm coronary artery CTA and "gold standard" CAG was 0.793;sensitivity and specificity for the diagnosis of coronary stenosis with 80 KV tube voltage combined IMR algorithm were 91.4%,of 93.9% respectively.Conclusions: 1.Compared with iDose4 and FBP technology,IMR technology can significantly improve the 80 KV and 100 KV of coronary artery CTA image quality.2.Application of IMR technology with low-dose coronary artery CTA on 256-slice MSCT to diagnose coronary stenosis rate is highly consistent with CAG examination;can be used in patients with BMI of 20-25 kg / m2 coronary artery imaging. |
PDF Full Text Request