| Objective To investigate the detection and improvement of the image quality of dual-layer detector spectrum CT virtual monoEnergetic(monoE)images in the small lesions of VX2 liver cancer model.Methods Hepatic VX2 double tumor models were established in 24 New Zealand white rabbits by CT guided puncture.All the rabbits underwent CT scan by using dual-layer detector CT to generate conventional 120-kVp polychromatic images and monochromatic images with energy levels from 40 to 100 keV during the arterial phase.The quantity of the lesion and measurement of the lesion length as well as the objective evaluation(signal noise ratio(SNR)and contrast noise ratio(CNR))and subjective evaluation(overall image quality score)of the image quality were measured by two radiologists.The results were compared with that of pathological examination.Result Pathology confirmed that 30 lesions were established,with an average size of 3.99±0.91 mm.18(47.40%)and 30(100%)lesions were detected at conventional images and monoE images with energy levels from 40 to 65 keV,respectively.The correlation between the length diameter of fresh pathological specimens and the measurements of lesion length diameter on 40(r=0.948,P=0.000)?45(r=0.958,P=0.000)?50(r=0.972,P=0.000)?55(r=0.952,P=0.000)?60(r=0.921,P=0.000).65 keV(r=0.917,P=0.000)monoE images was better than that on conventional images(P=0.270).The subjective evaluation of 40 45 50 55 keV monoE images quality were 4.50(0.50)(P=0.000)?5.00(0.00)(P=0.000)?5.00(0.50)(P=0.000)and 4.00(0.50)(P=0.002)respectively,which were significantly higher than the conventional mixed energy images 3.00(0.50).The objective evaluation of image quality showed that the SNR and CNR of monoE images decreased with the increase of the energy level of the monoE image.The CNR of monoE images with 40(P = 0.000),45(P = 0.002),50 keV(P=0.011)is higher than that of the conventional image.The CNR of monoE images with 40(P=0.000)?45(P=0.000)?50(P=0.000)?55 keV(P=0.002)is higher than that.of the conventional image.Conclusion Dual-layer detector spectrum CT monoE image in the low-energy state of 45?50kev can improve the detection rate of the small lesions of hepatic VX2 tumor models with better noise control and provide better image quality compared with conventional polychromatic images.Objective To investigate the clinical value and the performance of microwave ablation needle related metal artifacts reduction by detector-based spectral computed tomography using virtual monoEnergetic images.Methods Analysis of scanning images of 29 rabbit VX2 hepatocellular carcinoma models underwent percutaneous microwave ablation generated from detector-based spectral computed tomography.For conventional 120kVp polychromatic images and each virtual monoEnergetic images of different energy levels(40?60?80?100?120?140?160?180?200keV)were reconstructed and analyzed by two observers.Images that include both ablation needles and lesions and with the most severe artifacts were analyzed with regard to objective criteria(CT numbers in Hounsfield Units(CT 1 and CT 2),standard deviations(SD 1 and SD 2)and metal artifact index(AI1 and AI2)of the regions of interest(ROI1 and ROI2)of the most significant low density artifacts and high density artifacts;The CT value(CT 3 and CT 4)and standard deviations(SD 3 and SD 4)of the region of interest(ROI3)of the distant liver tissue less affected by artifacts and back muscles region of interest(ROI4)of in the same layer.Statistical analysis of the difference in the absolute value of CT values(ICT2-CT31)and the image noise of the distant liver tissue(SD3)between liver tissue around the ablation needle and liver tissue less affected by artifacts were performed.Subjective qualitative assessment of the image quality scored by a five-point Likert scale.Statistical analysis was performed to determine the difference in metal artifact reduction in conventional 120kVp polychromatic images and each virtual monoEnergetic images and to determine an optimal observation energy level.Results(1)When the energy level is>140 KeV,the Al1,AI2 and | CT2-CT3| of the virtual monoenergetic are lower than that of the conventional polychromatic images,the difference is statistically significant(p<0.05),and with the optimal observation energy level of 160?180 KeV;(2)When the energy level is?100 KeV,the SD3 in the virtual monoenergetic images is lower than that in the conventional polychromatic images,the difference is statistically significant(p<0.05),with the optimal observation energy level of 160?200 KeV;(3)When the energy level is ?120 KeV,the subjective image quality of the virtual monoenergetic images is better than that of the conventional polychromatic images,the difference is statistically significant(p<0.05),and optimal observation energy level is 160?180 KeV.Conclusion Dual-layer detector-based spectral CT using virtual monoEnergetic images detector can significantly reduce the microwave ablation needle related metal artifacts,As for virtual monoEnergetic images,160?180 keV may be the optimal energy level for the reduction of artefacts when the microwave ablation needle is punctured,which is beneficial to improve the image quality that shows the relationship between the ablation needle and the lesion and the surrounding important anatomical structures.Objective To explore the effects of single lesion ablation and combined with sorafenib treatment on distant lesions.Methods 48 Rabbit VX2 dual liver tumor model was established and finally enrolled.According to different therapeutic measures for interventional lesions,they were divided into 4 groups:Control group without any therapeutic treatment;MWA group was given percutaneous microwave ablation for;Sorafenib group was given oral treatment with Sorafenib daily;MWA+Sorafenib group was given combination therapy of percutaneous microwave ablation and daily oral Sorafenib;12 rabbits in each group.On the 1st,3rd,7th,and 14th days after the intervention,3 rabbits were sacrificed in each group.Measurement index:1.The long diameter(L),short diameter(D)and volume(V)of the lesions were observed preoperatively and on the 3rd,7th,and 14th postoperative days;2.The intensity of VEGF protein expression in immunohistochemistry;3.The mean microvessel density(MVD);4.Serum VEGF level.Statistical analysis was performed on t.he differences between each groups under each time point..Results 1.There was no significant.difference in lesions between the groups before surgery and on the third day after operation(p>0.05).Longer diameters of MWA+Sorafenib group,diameter and volume of MWA+Sorafenib group and MWA group were smaller than the control group at 7 days and 14 days(p<0.05);2.The expression of VEGF protein immunohistochemistry assay had difference in each group,but there was no statistical difference between the groups at each time point(p>0.05);3.The MVD counts in all groups increased significantly with time,and there was no statistically significant difference between the groups on postoperative 1,3,7 days(p>0.05).Sorafenib group and Sorafenib+MWA group were lower than the control group with statistical difference(p<0.05)4.Serum VEGF in each group increased significantly over time,on postoperative 1,3,7 days,there was no significant statistical difference between each groups(p>0.05).On the 7th postoperative day,the MWA group was lower than the control group,with statistical differences(p<0.05).On the 14th postoperative day,the Sorafenib+MWA group was lower than the control group,with statistical differences(p<0.05).Conclusion Single lesion ablation and single lesion ablation combined with sorafenib treatment in rabbit VX2 dual liver tumor model can inhibit the growth rate of distant lesions in the liver. |
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