| Part 1:The comparison study between 3.0T MR diffusion weighted imaging and the pathology of rabbit VX2 soft tissue tumor Objective:to compare the difference of apparent diffusion coefficient values between the parenchyma, necrosis, marginal zone and normal muscle tissue of VX2 rabbit soft tissue tumor at different time points, analysis the growth characteristics of the role of DWI,and the relationship between ADC on DWI and the pathology index.Methods:using direct planting method to establish VX2 rabbit legs soft tissue tumor model, a total of 20. The rabbits were perform on a GE 3.0T discovery 750 MRI scanner after successful inoculation on 7 days, 14 days, 21 days and 28 days. After obtaining images of T1 WI and T2 WI sequences, using a single-shot spin-echo planar imaging sequence scan multiple b-value DWI(b = 600,1000,1400). Place ROIs in tumor parenchyma, tumor necrosis, tumor fringe area and normal muscle tissue, to measure ADC values, taking the average of three measurements. After completion of MR scans,kill the model rabbits, measuring PCNA expression levels and labeling index. ADC evaluation and PCNA index correlations using Spearman correlation analysis. Use one-way ANOVA to compare ADC at different b values、different time points in tumor regions, necrotic area, marginal zone and normal muscle tissue.Results:Conventional MRI results: after 7、14、21 and 28 days, the maximum of tumor diameter was approximately 1.5、2.5、4.0 and 5.5 cm. Early stage of tumors(7、14days): small diameter, hard texture, less necrosis, edema light, less bleeding, on T2 WI and muscle tissue tumors were equal signal. Advanced stage of tumors(21、28days): volume increases, tumor heterogeneous high signal on T2 WI, central tumor necrosis, peritumoral edema.DWI and ADC Results: With the increase in the value of b, DWI SNR decline,b value of 600 s / mm2, the image is the sharpest; b value is relatively large(1400 s /mm2) SNR decreased; b value of 600, 1000 and 1400s/mm2,tumor parenchyma ADC values were significantly different(P<0.05), tumor ADC values of the marginal zone was no significant difference(P> 0.05), tumor necrosis and tumor parenchyma ADC values were significantly different(P<0.01), tumor parenchyma area and ADC values of normal muscle tissue statistically significant(P <0.01);when b value is 600 and 1000 s / mm2, ADC values were significantly lower than the tumor parenchyma central necrotic area and surrounding normal muscle tissue, the difference was statistically significant(P <0.05).Pathological findings: Early(7,14 days) gross tumor specimens showed homogeneous, less bleeding and necrosis; later(21, 28 days) gross specimen showed solid gray cut surface or fish-like brain samples with hemorrhage, necrosis, cystic change; are consistent with DWI signal performance graph.PCNA staining showed positive microscopic brown particles located in the nucleus of tumor cells.Conclusion:DWI can be active on the growth of soft tissue tumors dynamic monitoring,dynamic pathological changes in tumor response can be used to observe the VX2 rabbit limb soft tissue tumors, you can get a better picture when b value is 600 s /mm2, b value of 1000 and the 1400 s / mm2 when the image clarity declined although,but tumors showed more clearly. Solid tumor area, ADC values of normal muscle tissue necrosis and significantly different, ADC values reflect labeling index can be used to evaluate tumor cell proliferation. According to the characteristics of the appropriate application of each of these radiographic parameters can help determine the prognosis of soft tissue tumors, to guide and monitor the efficacy of treatment.Part 2:3.0T magnetic resonance diffusion weighted imaging in vivo monitor and evaluate effect of anti angiogenesis therapy on rabbitVX2 soft tissue tumor Objective:VX2 rabbit legs soft tissue tumor model to investigate the magnetic resonance diffusion-weighted imaging in vivo evaluation of tumor anti-angiogenic treatment feasibility and value.Method:After the establishment of direct farming VX2 rabbit thigh soft tissue tumor model, modeling one week after row MRI to determine the success of the rabbit model 20, after 7 days, 14 days, 21 days, 3.0T magnetic resonance scan, in addition to keeping the process a natural death, the remaining 12 single-blind, randomized into thalidomide antiangiogenic therapy group(n = 6) and control group(n = 6),once a day were given drinking water Thalidomide 200 mg / kg / day and saline200 ml / kg / day), for 7 consecutive days. The first day after the termination of treatment, performed MRI T1 WI, T2 WI, DWI, scanning sequence. Tumor sections CD3 l immunohistochemical staining. Statistics tumor ADC values of each group;tumor vascular morphology observed differences in each group.Result:Thalidomide treatment group tumor volume(1633.8±83.8) mm3, less than that of the control group(1741.3±38.1) mm3, but the difference was not statistically significant(P>0.05); after treatment in treatment group MRI image on the central necrosis area increased, a long T1 and long T2 signal, DWI signal around the central low, high signal; the control group there are substantial area of necrosis, but the increase in size, four T1 long T2 edema. The treatment group tumor ADC was(1.58±0.08)10-3mm2/s, higher than that of control group(1.32±0.05) 10-3mm2/s,there was significant difference(P<0.01); CD31 staining and IHS score of the treatment group(3.4±1.3) is lower than that of the control group(5.5±1.0), the difference was statistically significant(P<0.05).Conclusion:ADC value changes associated with tumor growth, necrosis of the biological process has some relevance; DWI reactive tissue activity and growth state of the tumor, anti-tumor angiogenesis therapy biological state also has some value judgment. |
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