Diffusion Weighted Imaging And Pathology Study Of Subcutaneous Hepatocelluar Carcinoma Bearing Nude Mice Model

BACKGROUD:Primary hepatocellular carcinoma is one of common malignant tumors in China, and the mortality of hepatocellular carcinoma is high. Angiogenesis is the prerequisite of generation, progression, invasion and metastasis of malignant tumor, the close correlation of angiogenesis and the tumor biological behavior and degree of malignancy has been identified. Architechture and function of vessel result in the alteration of MR features. We establish the hepatocellular carcinoma nude mice model and perform MR diffusion weighted imaging(DWI)examination in different growth periods, and compare the distinction of signal intensities on DWI and their pathologic changes for explore the value of DWI for monitoring the growth characteristic of hepatocellular carcinoma nude mice model; And we compare the distinction of apparent diffusion coefficient ADC) value and exponent apparent diffusion coefficient(eADC) value in surrounding solid components of subcutaneous tumor in different periods and their variation pattern, analyze the correlation between ADC, eADC value and the microvessel density in surrounding solid components of tumor in different growth periods, and perform MR diffusion weighted imaging(DWI) examination to the hepatocellular carcinoma nude mice model, which is underwent anti-angiogenic drug treatment, analyze the correlation between ADC, eADC value and the microvessel density in surrounding solid components of tumor in treat group and contrast group, then explore the pathologic basement on which solid components of tunlor showed different ADC and cADC values and assess the value of DWI to monitor progression, prognosis and therapeutic effect of maligment tumor.METHODS:Thirty BACB/C-nu/nu nude mice were randomly divided into three groups (each n=10), named group A,group B and group C, which is performed conventional MR and MR diffusion weighted imaging(DWI) examination in the fifty, thirty and fourty-five day respectively after that tumor tissue mass of 2 mm3 was injected into cutaneous of nude mice. After axial T2WIFSE,coronal T2WIFSE and coronal T1WIFSE were performed, single-shot spin-echo echo-planar diffusion-weighted imaging was performed with two different b values(400s/mm2,800s/mm2), After DWI examination performed, DWI and ADC maps of hepatocellular carcinoma nude mice model in different periods were obtained, and then the values of ADC with different b value were measured and the values of eADC corresponding were calculated in surrounding solid components in tumor respectively.all mices were sacrificed after exams were finished, and the tumors were removed and stained with hematoxylin and CD34 after MR examination, then we count the microvessel density and analyze the correlation between ADC, eADC value and the microvessel density.Twelve BACB/C-nu/nu nude mice after implantation were randomly divided into treat group and contrast group (each n=6). Thirtieth day after successful cultivation, treatment group and control group were treated by injecting endostatin and saline intraperitoneally respectively in 14 days. Mices in each group were performed conventional MR and DWI after 16 days, DWI and ADC maps of tumors were obtained, and then the values of ADC with different b value were measured and the values of eADC corresponding were calculated in surrounding solid components in tumor respectively.all mices were sacrificed after exams were finished and the tumors were removed and stained with hematoxylin and CD34 after MR examination, then we count the microvessel density. The change in tumur volume of the treatment group and control group was measured, and inhibiting rate was calculated. Then we analyze the correlation between ADC, eADC value and the microvessel density.RESULT:Ⅰ.The successful rate of transplantation 2mm3 tumor tissue mass method of was 100%.Ⅱ.On conventional MR scanning, all tumors in different growth periods showed slightly long T1 and slightly long or long T2 signal intensities with clear margin. The singal of tumors in group A was homogeneously, and the singal of tumors in group B and C was uneven, which demonstrated patchly long T2 signal intensity in their central part. The average volume of the tumors in the three groups(group A,B,C) was 0.11cm3, 0.44cm3,0.79cm3 respectively, tumor growth rate (TGR) is 300%, doubling time (TD) was 3.8 days.Ⅲ. All tumors showed obviously homogeneously high signal intensity with clear margin on DWI.Ⅳ. The DWI images can clearly show tumors with two different b values, the SIR of tumors increased and the SNR and CNR decreased with b value of 800s/mm2 compare to that with b value of 400s/mm2.Ⅴ.On ADC maps, all tumors in the group A showed relatively homogeneously signal intensity with blue, and all tumors in the group B and C showed relatively uneven signal intensity with green, and demonstrated patchly red and yellow in their central part, especially in the group C. VI. With the progress of growth time, the ADC values with different b value in surrounding solid components of tumor decreased,and the eADC values increased.Ⅷ. With b value of 400s/mm2, there was positive correlation between ADC value and MVD value of surrounding solid components of tumor in all groups, and there was negative correlation between eADC value and MVD value. With b value of 800s/mm2, there were no correlation between ADC value,eADC value and MVD value of surrounding solid components of tumor in all groups.Ⅰ.All mices in the treat group and contrast group were generally good after treatment, and there were no significant difference in weight change between two groups before and after treatment.Ⅱ. The tumor volume of treat group and contrast group is 0.65±0.32cm3,0.82±0.25cm3, respectively, and there were signifycant differences between two groups (P<0.05). Inhibiting rate is 32%.Ⅲ.On conventional MR scanning, all tumors in both groups showed long T1 and long T2 signal intensities with clear margin,the singal was uneven, which demonstrated patchly long T2 signal intensity in their central part.Ⅳ.All tumors in both groups showed obviously homogeneously high signal intensity with clear margin on DWI.Ⅴ. On ADC maps, all tumors in the treat group and contrast group showed relatively uneven green-based nodules, which demonstrated patchly red and yellow in their central part.Ⅵ. The ADC values of treat group in surrounding solid components of tumor was higher than which of control group, and the eADC value of treat group was lower, and there were signifycant differences between two groups (P<0.05).Ⅷ. There was positive correlation between ADC value and MVD value of surrounding solid components of tumor in both treat group and contrast group, and there was negative correlation between eADC value and MVD value.CONCLUSIONS:This study demonstrate that:①The high quality DWI images can clearly show the size of tumor,which were obtianed from using clinica 1.5T MRI and 1.5T4 channel animal coil. The ADC map could be a true reflection of the general pathological features of tumor growth, and could show the cystic and necrotic areas with typical imaging features in early time, and plays an important value in dynamic detection of genesis and development and the growth characteristic of the tumor.②The quantitative indicators (ADC values and eADC values)can reflect the difference between the pathological basis at the cellular level③DWI images and the quantitative indicators can monitor the treatment efficacy of endostain④.MVD value of tumor in hepatocellular carcinoma nude mice model had impacts on the measurement of ADC value on DWI With small b value, In reverse, ADC value from small b value reflected the blood perfusion supply and MVD of tumor in hepatocellular carcinoma nude mice model to some degree, and will possiblely indirect judge tumor biological behavior, prognosis and monitore efficacy of some anti-angiogenesis trearment.