| Objective: to analyze the impact of ASIR-V algorithm on signal,noise,image quality and radiation dose of coronary computed tomography angiography.Methods: 121 consecutive patients underwent clinically indicated coronary computed tomography angiography(Revolution CT;GE Healthcare)from 12.2018 to 11.2019.The subjects included in this study had a heart rate below 80 beats / min before scanning,BMI 20-30kg/?,and then divided into four groups according to ASIR-V50%,60%,70%,and 80%.The optimal diastolic phase and optimal systolic phase are automatically selected during the acquisition phase.The tube voltage is uniformly set to 100 kv during scanning.The SmartmA automatic tube current Results: modulation is used to achieve a threshold of 245 HU and delay the enhanced scan for 12 s.After scanning,all images are transmitted to AW4.6 workstation for image post-processing.the machine automatically generates volume CT dose index CTDIvol and dose length product DLP,and according to the formula effective dose ED(mSv)= k(mSv mGy-1 cm-1) DLP(mGy cm),k is 0.014 when calculating the ED value,meanwhile,objective evaluation and analysis are performed on the four groups of CT original cross-sectional images,and the ascending aortic root noise(BN),Contrast the noise ratio(CNR)and the signal-to-noise ratio(SNR).Similarly a four-point Likert image quality score of coronary segments was graded for each dataset and compared.Differences between groups were analyzed by chi-square test,comparisons between groups were analyzed by variance F test,and rank data using Kruskal-Wallis nonparametric rank sum test.Correlation analysis was performed by Spearman rank correlation analysis of graded data.A cutoff value of P < 0.05 was considered statistically significant.(1)The general data of the four groups of patients were not statistically significant(P> 0.05),and the baseline data of the four groups were consistent and comparable.(2)The comparison of the radiation dose index ED between the four groups showed that the radiation dose ED of the four groups showed that the group A was 4.68 2.01 HU,the group B was 3.68 1.22 HU,the group C was 3.57 0.97HU;the group D was 3.22 1.92 HU.Compared with ASIR-V50% group,ASIR-V60% group decreased by 21.4%,the difference was statistically significant(P <0.05),and Spearman rank correlation analysis showed that ED was negatively correlated with ASIR-V weight(r <0,P < 0.05).(3)The objective evaluation indicators SNR,CNR,and BN of the image quality are relatively visible among the four groups,and the objective evaluation indicators SNR,CNR,and BN of the image quality are relatively visible.The signal-to-noise ratio SNR: Groups B,C,and D are significantly larger than those of Group A,and Group B increased significantly;contrast noise ratio CNR: group D was significantly higher than group A;noise BN was the largest at 50% of ASIR-V,P <0.05,indicating statistical significance.(4)Subjective scoring of image quality,according to the 15-segment coronary segmentation method,there are 384 segments in ASIR-V50% group,336 segments in ASIR-V60% group,and ASIR-V70% group There are 360 segments,and there are 339 segments in the ASIR-V80% group.The overall difference is different.The ASIR-V60% score is the highest and the 80% score is the lowest.There were no cases with a score of 1 in the four groups.See Table 6 for details.It can be seen from Figure 5 that the four groups of coronary tree images are not significantly different from the naked eye.The ASIR-V80% group has a slightly rough distal blood vessel;as shown in Figure 6-8: CPR and CPR of the right coronary and left anterior descending branch CP image showed good blood vessel clarity,and the distal vessels of ASIR-V80% were slightly blurred.CPR and CP images of the left circumflex branch showed ASIR-V70%,and 80% of the image vessels were blurred compared to ASIR-V50% and 60%.The edges are not sharp,especially in the ASIR-V80% group with arterial artifacts.Conclusions: Reconstruction with ASIR-V 60% on CCTA provides the optimal balance between image noise,SNR,CNR,image quality,and effective dose. |
PDF Full Text Request