ABSTRACT
Objective To investigate dynamically characteristics of apparent diffusion coefficient (ADC) of MR diffusion-weighted imaging (DWI) in the rabbit VX-2 tumor model.Methods Forty New Zealand rabbits were included in the study and forty-seven rabbit VX-2 tumor models were raised by implanting directly and intrahepatically after abdominal cavity was opened.DWI was carried out periodically and respectively on seventh,fourteenth,and twenty-first day after implantation.Part samples of VX-2 tumors were studied by pathology.The distinction of VX-2 tumors on DWI was assessed by their ADC values.The statistical significance between different time groups,different area groups,or different b-value groups was calculated using SPSS12.0 software,respectively.Results ADC values of 47 VX-2 tumors in the area of tumor periphery,tumor center,and normal parenchyma around tumor were greater when b-value was 100 s/mm2 than those when b-value was 300 s/mm2 and the distinction of VX-2 tumor ADC in the area of tumor periphery,tumor center,and normal parenchyma around tumor between different b-value groups was significant,respectively( F =17.964,P ＜0.01 ; F =13.986,P ＜0.01 ; F =128.681,P ＜0.01 ).The ADC values in the area of normal liver parenchyma around tumor were greater than those in the area of VX-2 tumor periphery and tumor center when the b-value was 100 or 300 s/mm2.When b-value was the same( 100 or 300 s/mm2),the distinction of VX-2 tumor ADC between different areas was significant( F =176.586,P ＜0.01 ; F =55.089,P ＜0.01 ).The ADC of VX-2 tumor in the area of tumor periphery and tumor center became gradually low from seventh to fourteenth or twenty-first day after implantation and the distinction of ADC between different time groups but the area same (?) was significant( b =100 s/mm2,F =48.211,P ＜0.01 ;b =300 s/mm2,F =20.955,P ＜0.01 ).There were not obvious cellular necrosis in VX-2 tumors on seventh and fourteenth day after implantation but ADC of VX-2 tumor decreased unobviously because of cellular edemata in or around tumors.There were obvious cellular necrotic areas in VX-2 tumors on the twenty-first day after implantation.ADC of viable tumor cells in VX-2 tumors were lower on DWI than that in the area of normal liver parenchyma around tumor and ADC of dead tumor cells in VX-2 tumors were unequal,including high values,equal values,and low values but they were higher than that in the area of normal liver parenchyma around tumor after dead tumor cells had been liquified or had become cystic.Conclusions ADC is able to reflect objectively the diffusion of water molecules in the tumor and to reflect indirectly the degree of the growth and liquified necrosis of a tumor.ADC has an important and potential value in monitoring dynamical tumor growth and in evaluating malignant degree and therapeutic effect.
ABSTRACT
ObjectiveTo investigate its dynamic characteristics and pathological mechanism on magnatic resonance diffusion weighted imaging (DWI) after chemoembolization in rabbit liver VX-2 tumor model.MethodsForty New Zealand rabbits were included in the study and forty-seven rabbit VX-2 tumor models were raised by implanting directly and intrahepatically after abdominal cavity was opened.Forty VX-2 tumor models from them were divided into four groups.DWI was performed periodically and respectively for each group after chemoembolization.All VX-2 tumor samples of each group were studied by pathology.The distinction of VX-2 tumors on DWI was assessed by their apparent diffusion coefficient (ADC) values.The statistical significance between different time groups,different area groups,or different b-value groups was calculated using SPSS 12.0 software.ResultsWhen b-value was 100 s/mm2,ADC values in the area of VX-2 tumor periphery,VX-2 tumor central,or normal liver parenchyma around tumor became gradually low in sixteen hours after chemoembolization,and were the lowest at sixteenth hour,and then they increased gradually from sixteenth hour to fourty-eighth hour after chemoembolization.The distinction of ADC between different time groups was significant,respectively ( F =7.325,P ＜ 0.01 ; F =2.496,P ＜ 0.05 ; F =6.856,P ＜0.01 ).Cellular edema in the area of VX-2 tumor periphery or normal liver parenchyma around tumor increased quickly in sixteen hours after chemoembolization; however,from sixteenth hour to forty-eighth hour,cellular edema in the area of normal liver parenchyma around tumor decreased gradually and that in the area of VX-2 tumor periphery decreased lightly at first and then increased continually.Cellular necrosis in the area of VX-2 tumor periphery after chemoembolization was more significant than that before chemoembolization.The areas of dead cells in VX-2 tumors manifested low signal and high ADC value while the areas of viable cells manifested high signal and low ADC value.ConclusionsDWI is able to detect and discriminate tumor necrotic areas from viable cellular areas before and after chemoembolization.ADC of normal liver parenchyma and VX-2 tumor are influenced by intracellular edema,tissue cellular death,and microcirculation disturbance after chemoembolization.
ABSTRACT
Objective To examine the relationships between a number of potential risk or protective factors and the risk of depression and anxiety among a population of adolescent elite athletes in Guangzhou city. Methods A whole sample was consisted of 520 students,and the information of their age,gender,characteristics and others was investigated. Anxiety and depression were assessed using the Hospital Anxiety and Depression Scales(HADS). Data were analyzed using multiple stepwise regression analysis. Results After adjusting for other variables,students who had a high risk of anxiety were underweight (sβ =2.482) when compared to those who were of normal weight. Reduced risk of anxiety was associated with older students ( sβ = 4. 365), students with moderate educated mothersβ=3. 153) , and students who perceived very high pressure from teachers/coaches (sβ=5.372). A significant increase in the risk of depression was associated with variables including: students aged between 15 and 16 years(sβ =3.367) ,students who had a family history of chronic diseases (sβ =2.765) , and poor overall support(sβ = 4.365). Reduced risk of depression was associated with students with moderate educated mothers( sβ = 6.764) and students who perceived very high pressure from teachers/coaches(sβ = 4. 167). Conclusion Various risk and protective factors have been identified for anxiety and depression. These results have direct implications on the development of appropriate preventive strategies for mental problems among young elite athletes.