| Objective:To explore the value of sinogram affirmed iterative reconstruction(SAFIRE)technique of low kVp CT enhancement scan in liver.Methods:Image data and clinical material were analyzed retrospectively in the59 subjects,and all of the subjects were underwent CT enhancement scan in superior abdomen for all kinds of reasons in the Affiliated Hospital of Guizhou Medical University from July 2015 to June 2016.In accordance with the different tube voltage,the subjects were divided into group A(120kVp)and group B(80kVp),group A of 29 cases,16 cases were male,13 cases were female,aged 39 to 79 years old,the average age was(55.79±10.96)years old;Group B of 30 cases,18 cases were male,12 cases were female,aged 32 to 79 years old,the average age(56.93±13.71)years old,body mass index in all subjects(BMI)were 18.5~24kg/m2.All the subjects were scanned with SIEMENS 128-row spiral CT.All of them were scanned by axial scanning.The scanning range was from the top of the diaphragm to the lower edge of the liver.Group A of 29 subjects were scanned by 120 kVp and filtered back projection(FBP)reconstruction;Group B of30 subjects were scanned by 80 kVp and SAFIRE reconstruction with strength grade1-5.A total of 6 groups of reconstructed images were obtained.The convolution kernel were B40 f and I40 f,the reconstructed layer thickness was 1.0mm,the interval was 1.0mm.The data analysis and measurement were performed on the Siemens post-processing station Syngo MMWP(Version 2008A).In the arterial phase image,the hepatic portal level was selected to measure the liver CT value and air CT value.The volume CT dose index(CTDIvol)and the dose length product(DLP)on the CT device were recorded.CTDIvol?DLP and effective dose(ED)and the evaluation index of image quality were compared between two groups ofA and B.Objective evaluation of the image quality were liver CT value,image noise and signal to noise ratio(SNR).Subjective evaluation of the image quality were subjective score of image noise,vessel conspicuity,artifacts and overall image quality.SPPSS19.0 software was used for statistical analysis.The CTDIvol?DLP and ED of group A and group B were analyzed by independent t test.The intergroup comparison of the objective and subjective evaluation index of 6 groups were analyzed by ANOVA,and the LSD method was used in the intra-group comparison.Results: CTDIvol?DLP and ED were difference between two groups(all P?0.05).Compared with group A,group B were decreased by 40.33% in effective dose.There were no differences in the CT value of 6 groups(all P?0.05).There were differences in the SD and SNR between 6 groups(all P?0.05).After intra-group comparison,The liver CT values of groups B1 ~ B5 and group A were differences(all P?0.05).But,There were no differences in liver CT values between the groups B1 ~B5(all P?0.05).There were differences in SD and SNR between the group B5 and the other groups(all P?0.05).The image noise in group B5 is the smallest and the SNR is the biggest.The subjective scores of 6 groups had differences(all P?0.05).The scores of image noise,vessel conspicuity and hardening artifacts in group B5 were higher than those in other groups,but the score of “waxy” artifacts was lower than that of other groups(all P?0.05).The score of overall image quality in group B3 was the highest(all P?0.05).Conclusion:Image quality of 80 kVp liver CT enhancement scan combined with SAFIRE-3 technique could get better image,and reduce effective dose. |
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