| Objective:To explore the clinical value of three-phase virtual non-enhanced image and true non-enhanced image in image quality,lesion detection rate and radiation dose.Method:A total of 28 patients were enrolled in the three-phase dual-energy mode scan of the liver from October to November in Liao ning Provincial People's Hospital.Among them,16 males and 12 females aged 25-80 years were collected.All patients' livers were performed using single-energy portal and delayed phase scan with a second-generation DECT scanner(Siemens SOMATOM Definition Flash;Siemens Medical Solutions,Forcheim,Germany).Single-energy conventional scanning scan parameters: tube voltage is 120 KV,tube current is 260 mAs.Double-energy mode enhanced scan parameters when scanning: A tube ball tube voltage is 100 KV,tube current is 230mAs;B tube ball tube voltage is sn140 KV,tube current is 178 mAs.The two groups original data(100KV and sn140KV)of different phases' enhancement scan of dual energy models are automatically transferred to the Syngovia VIA130362 post-processing station,and the Liver VNC application is selected in the Dual-energy software.The special post-processing software algorithm is used to obtain the virtual non-enhanced image in liver's different phases,adjusting the image's window width and window level as the same with conventional scan,the four groups of true non-enhanced images into the ordinary reading browser to save.The standard deviation of the CT values,CT values of the liver,erector spinae and abdominal aorta were measured and signal-to-noise ratio(SNR)as well as contrast to noise ratio(CNR)were calculated by a radiologist in the same place of the same level of four sets of non-enhanced images,while recording the numbers and type of liver lesions,dose length product(DLP)generated automatically from CT scanner.The two senior radiologists that are good at diagnosis in abdominal CT imaging independently score for four groups of non-enhanced images in the PACS system.If the scores are different,the results are agreed by both parties.The CT value,SD value,SNR,CNR,image quality score,DLP and ED of four groups non-enhanced images were analyzed by one-way ANOVA using SPSS20.0 statistical software.The results were expressed using means±SDs standard deviation.The lesion detection rate of the four groups of images was analyzed by chi-square test.P<0.05 indicated a statistically significant difference.Result1.Image quality assessment1.1 Subjective image quality scoreThe image quality of TNE was higher than that of arterial,portal and delayed phase VNE image(P=0.00);No significant differences were observed among three groups of VNE image(P>0.05).The score of image quality of TNE was 4.82±0.39.The score of image quality in arterial,portal and delayed phase VNE image was 4.04±0.33,3.82±0.39,3.93±0.26,respectively.1.2 Objective image quality analysisThe average of CT values of the liver were(56.98±6.12)HU?(56.48±5.89)HU?(56.94±6.43)HU?(56.98±7.25)HU in TNE image,arterial,portal and delayed phase VNE image,respectively.There was no significant difference in average of CT value between the four groups non-enhanced images(P>0.05).The average CT value of erector spinae muscle the of VNE image was higher than that of three groups TNE images;The average CT value of erector spinae muscle of TNE image and three groups VNE images were statistically significant difference(P=0.00).There was no significant difference in average the CT value among the three groups of VNE images(P> 0.05).There was no significant difference in the CT value of abdominal aorta between TNE and VNE images(P>0.05).The CT values of the abdominal aorta were significantly higher in true non-enhanced image and arterial phase the VNE images than those in the portal phase and the delayed phase VNE images,the difference was statistically significant(P<0.05).The SNR and CNR of the all three groups of VNE images were higher than those of the TNE images,the difference was statistically significant(P=0.00).There was no significant difference in SNR and CNR among the three groups of VNE images(P>0.05).The SD value in all three groups of VNE images were lower than that of TNE images(P<0.05).There was no significant difference at the noise among the three groups of VNE images(P>0.05).2.The detection rate of liver lesionThe three-phase dual-energy enhanced scan images were combined to show the lesion as a reference standard.Four groups of non-enhanced images had consistent lesion detection rate.A total of 32(detection rate of 69.56%)were detected in each group,including cavernous hemangioma 7(detection rate of 43.75%),liver cyst 16(detection rate of 76.19%),liver metastases 4(detection rate of 100%),liver cancer lesions 2(detection rate of 100%),liver abscess 1(detection rate of 100%),intrahepatic calcification or intrahepatic bile duct stones 2(detection rate of 100%).3.Radiation doseThere was no significant difference in average DLP and ED values among the four groups of non-enhanced images(P>0.05).The effective dose of TNE images,arterial,portal and delayed VNE images was(3.45±0.73)mSv,(3.40±0.73)mSv,(3.39±0.73)mSv,(3.41±0.75)mSv,respectively.The total of ED value in true non-enhanced was 96.85 mSv,the total of ED value in arterial phase virtual non-enhanced was 95.38 mSv,the total of ED value in portal virtual non-enhanced was 95.14 mSv,and the total of ED value in delayed phase virtual non-enhanced was 95.55 mSv.If the non-enhanced scan was eliminated,the effective dose was reduce by 25% in enhanced scan of liver.Conclusion: Liver three-phase virtual non-enhanced images quality can meet the clinical diagnostic requirements,and it has a consistent lesion detection rate with true non-enhanced image;It is possible to any one of the liver virtual non-enhanced instead of true non-enhanced to reduce the patient radiation dose,with potential clinical application value. |
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