A Preliminary Study On The Removal Of Subclavian Vein Artifacts In Enhanced Chest Scan By Gem CT Energy Spectrum Imaging

Objective: to investigate the optimal single energy level of energy spectrum CT imaging(GSI)for the removal of subclavian vein contrast agent(BHA)in enhanced chest CT images.Methods: Collect the December 2018 to June 2019,a total of 40 cases of adult patients,chest enhanced HDCT spectroscopy(GSI)scanning,scan data in workstations to GSI viewer to rebuild the image of a hybrid energy 140 kv(kVp)and 11 groups of single energy image(40 ~ 140 electron volts keV,every 10 keV reconstruction group 1),each 12 groups of images can be obtained,select each set of images within subclavian vein by the artifacts of the most serious level,Select three anatomical position(pectoralis major and small chest muscle and subscapularis)interested in draw false shadow area(ROI),pick two position and in the aspect of the contralateral aortic arch(pectoralis major,armpit fat)delimit the background area ROI,a total of five ROI and measurement noise(SD)of each ROI and CT value,respectively,to calculate the 12 groups of pseudo image shadow noise,CT value difference,contrast to noise ratio(CNR)and BHA,and carries on the single factor analysis of variance between groups for statistical analysis.Results: compared with 140 KVP hybrid energy image and 11 groups of single image artifact noise,CT value difference,contrast to noise ratio(CNR)and BHA,it is concluded that 70 kev image has the highest CNR,was 7.14(P<0.01),which can keep a good soft tissue contrast,contrast medium enhancement effect is good,but the BHA is relatively high,CT value difference,respectively(20.44)and(46.79)HU,images are greatly influenced by the artifacts.At 40-140 kev,with the increase of every 10 keV,the BHA gradually decreases and its ability to remove the hard artifact of the beam is gradually enhanced.120 keV can remove the contrast agent hardening artifact to themaximum extent with the minimum CT value difference(P < 0.01).The difference between BHA and CT values is(13.58)and(8.86)HU,respectively,but the CNR of120 keV is slightly lower than that of 70 keV.Conclusion: energy spectrum CT single energy imaging can effectively remove the beam hardening artifacts generated by iodine contrast agent,reduce image noise,and improve image quality.