| Objective To stimate the image quality ?renal mass and radiation dose of cortex,medulla and delayed phase of dual-energy virtual non-contrast and of true non-contrast.To investigate the feasibility of the virtual unenhanced replacing the true non-contrast and the advantages and disadvantages of dual-energy virtual unenhanced.Methods a total of 80 cases were collected from the First Affiliated Hospital of Anhui Medical University with three phases doul-energy enhanced scan.The conventional scan was performed in a single energy mode(120kV,mA automatic adaptation).In the cortical phase,medullary phase and delayed phase,the dual-energy mode(140/80 kV rapidly switching,260mA)was adopted.The original images of the three phases dual-energy enhanced was transmitted to the PACS system by the thickness of 1.25 mm,which was built by the 50%ASIR method.The three phases of dual-energy enhanced images were sent into GE ADW4.5 workstation,the iodine-water separation automaticly by GSI Viewer software,iodine and water-based map respectively were producted,choosing water-based map as virtual unenhanced images: cortical virtual unenhanced(VUEa),medullary virtual unenhanced(VUEv),delayed phase virtual unenhanced(VUEd).Two experienced radiologists were invited to evaluate blindly the image noise and artifact,image anatomic details and lesion display,respectively.The four groups were scored.A resident was asked to measure the maximum diameter of each lesion,draw the ROI,measure and record the SD,CT,radiation dose(CTDIvol,DLP),calculate the detected rate of masses,effective dose ED,SNR and CNR of four groups respectively.The consistency of two physicians were tested,the image quality score,lesion size,lesion number and detection rate,SD,SNR and CNR,radiation dose of the true non-contrast and three virtual unenhanced images were analyzed,P < 0.05 was statistically significant.Results the consistency of two doctors about the noise and artifact score and anatomic details and of the lesion display score were very good in four groups,all of which were > 0.8.There was no statistical difference between the true unenhanced and the virtual unenhanced(P > 0.05).The score of image noise and artifact was significantly different between the true unenhanced and the virtual unenhanced(P < 0.05).The score of noise and artifact of three groups of virtual unenhanced images were all higher than those of true unenhanced images.There was no statistically difference in the number,size and detection rate of stone or calcification,cysts,fat lesions and fat free lesions between the true unenhanced and the virtual unenhanced images(P > 0.05).SD,SNR and CNR between true unenhanced and three phases VNC images were statistically different(P < 0.05),SD and SNR of three virtual unenhanced images were higher than the true unenhanced image,SD : 21.87 + 18.74,23.10 + 20.25,22.40 + 18.4,14.78 + 17.83,SNR :53.93 + 18.85,54.37 + 15.97,54.93 + 15.55,5.16 + 9.92,respectively.The CNR of three VNC images were lower than those of the true unenhanced image,which were 7.74 + 11.10,5.93 + 5.39,6.10 + 4.98 and 15.96 + 11.15,respectively.The CTDIvol,DLP and ED of true unenhanced and three VNC images were statistically different(P < 0.05),radiation dose of three VNC were lower than the true unenhanced,CTDIvol : 6.48±0.00?6.48±0.00?6.48±0.00?11.52±1.42,DLP:172.64±14.24?172.64±14.24?171.00±19.54?305.97±51.68,ED = 2.59 + 0.21,2.59 + 0.21,2.57 + 0.29,4.59 + 0.78,respecti vely.Insteading of the true unenhanced,total radiation dose of CTDIvol,DLP and ED were decreased by 57.82% by using dual-energy virtual unenhanced.Conclusion the artifacts in three virtual unenhanced images was higher than true unenhanced image,and CNR were lower than true unenhanced,but there were no obvious difference in the detection rate of lesions in four groups,the VNC image can meet the requirement of diagnosis,and the radiation dose significantly was lower than true unenhanced,can instead true unenhanced feasibly,and VNC has potential clinical application prospect.Although there was no significant difference in the image quality,lesion display and radiation dose between the three phases of virtual unenhanced,VUEa were closer to the TNE.Therefore,we recommend that the cortex phase is fit to product virtual unenhanced. |
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