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Objective:To investigate the effect of deviation from the isocenter point on the quality of CT images at the same radiation dose.Methods:A 160-layer CT scanner was used to scan the phantom at isocenter and deviations of 3, 6, 9, 12 and 15 cm. CT was performed with the following parameters: 120 kVp; 400 mAs; slice thickness, 1 mm; and slice increment, 1 mm. Images were reconstructed using the filtered back projection algorithm. Noise power spectrum (NPS), task transfer function (TTF) and detectability index (d′) were measured. NPS peak was used to quantify the noise magnitude and TTF 50% was used to quantify the spatial resolution. NPS, TTF and d′ were compared using one-way ANOVA. Results:The NPS average spatial frequency, spatial resolution and d′ values gradually decreased as the offset distance increased and the amount of noise increased. NPS peak at isocenter and deviations of 3 cm, 6 cm, 9 cm, 12 cm and 15 cm were (94.31±1.48), (104.25±1.46), (131.44±1.96), (171.86±1.91), (224.05±1.37), (286.51±2.09)HU 2·mm 2, respectively ( F=37 241.91, P<0.001). And d′ values of 2 mm low-contrast lesions were 3.51±0.06, 3.31±0.04, 3.01±0.04, 2.59±0.06, 2.21±0.03, 1.88±0.03, respectively. The reduction in spatial resolution was more pronounced for high contrast, and the d′ values decreased to a similar extent for various types of lesions. The noise was increased by about 82%, the high contrast spatial resolution was decreased by about 12%, and the d′ value was decreased by about 26% at 9 cm from the isocenter point (all P<0.05). The noise was increased by about 204%, the high contrast spatial resolution was decreased by about 27%, and the d′ value was decreased by about 45% at 15 cm from the isocenter (all P<0.05). Conclusion:The CT image quality was decreased with the increase of the offset distance from the CT isocenter point. The image quality was severely compromised at offset distances greater than 9 cm.
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Objective:To observe the role of lamividine and silymarin preventing and curing liver fibrosisrelevant factors induced by alcohol drinking in hepatitis B virus (HBV) transgenic mice (Tg mice).Methods:Forty HBV-Tg BALB/C mice with 1.3 copy were randomly divided into 4 groups:a control group,a model group,a lamivudine group and a silymarin group.Tg mice in control group were treated with normal saline via intragastric administration;Tg-mice in the model group were treated with 50％ alcohol (5 mL/kg) once a day via intragastric administration;while Tg-mice in lamivudine group and silymarin group were treated with alcohol (5 mL/kg) plus laminvudine (100 mg/kg) and silymarin (200 mg/kg) once a day via intragastric administration respectively.All groups were raised for 10 weeks.The levels of HBV-DNA copy number,ALT,AST in serum,the degree of inflammation,the degree of fibrosis,the mRNA expression levels of TGF-β 1,Smad3,Smad7 and connective tissue growth factor (CTGF),and the protein expression levels of TGF-β1,CTGF and α-SMA in liver tissue were detected.All the images were scanned with electronic computer and the data were analyzed with SPSS13.0 software.Results:Compared with the control group,liver injury were significantly aggravated,while HBVDNA copies,mRNA levels ofTGF-β1,Smad3,Smad7 and CTGF as well as the protein levels of TGF-β1,CTGF and α-SMA were significantly increased (P＜0.05).Compared with the model group,liver injury were significantly attenuated in silymarine group and lamivudine group,while mRNA levels of TGF-β 1,Smad3 and CTGF as well as the protein levels of TGF-β1,CTGF and α-SMA were significantly decreased;mRNA level of Smad7 was further increased (P＜0.05);the levels of ALT and AST in serum were decreased in the silymarine group (P＜0.05).Conclusion:Lamivudine and silymarin relieve the histological damage in the liver of alcohol-fed Tg mice.The mechanisms for the beneficial effects of lamivudine or silymarin might be related to inhibiting the expression of TGF-β 1,Smad3 and CTGF,modulating the expression of Smads and suppressing the activation of HSC.
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Aim To investigate the synergistic effects and possible molecular mechanism of hepatitis B virus (HBV) and alcohol on liver injury in HBV transgenic mice(HBV-Tg mice).Methods 20 HBV-Tg mice and 20 wild-type mice were randomly divided into 4 groups:alcohol-fed Tg mice and alcohol-fed Wt mice, and they were given intragastric administration with alcohol. Control Tg mice and control Wt mice received intragastric administration with saline.All groups were rasied for 10 weeks.The levels of ALT and AST in serum, the degree of inflammation, the degree of fibrosis, the mRNA expression of TGF-β_1, Smad3, Smad7, CTGF and the protein expression of TGF-β_1, CTGF, α-SMA in liver tissue were detected.Results The serumlevel of ALT and AST, the mRNA expression of TGF-β_1, Smad3, Smad7, CTGF and the protein expression of TGF-β_1, CTGF, α-SMA in liver all increased markedly in alcohol-fed Tg mice. Alcohol consumption induced hepatocyte steatosis and hepatic inflammation in alcohol-fed Tg mice, but the change of liver fibrosis was not remarkable.Conclusion HBV and alcohol have synergistic effects on early liver injury, possibly by enhancing the expression of TGF-β_1, Smad3, CTGF, α-SMA and inducing unbalanced expression of Smads.