| Cerebral neoplasm is not the most common neoplasm in human, but its mortality and disability is very high, esp., the most common malignant glioma, which prognosis has not been improved since the 70s last century. This fully reflects the fact that we lack the knowledge about biological mechanism of glioma pathogenesis and development, resulting in not effectively treating. So, it is necessary and obligatory to highlight the basic study of glioma at the present time.Like all other tumors, glioma can also be classified into three parts, that is, tumor cells, interstitial tissue, and tumor neovascularity. Prior studies focused on biological and pathological changes of tumor cells, but the tumor angiogenesis is increasingly paid attention in recent years, because of more knowledge about tumor angiogenesis having an effect on infiltrative growth, diagnosis, management and prognosis of glioma.CT perfusion is used widely because of its fast scanning, available perfusion software, high spatial and resolution, and simple technique.Prior observation of glioma is limited to pathological examination of surgical specimen, advanced stage of tumor. Owing to lack of continuous observation, it is not to perform in vivo study, and also is difficult to predict the related biological changes. However, it is feasible to dynamically to observe the development process of glioma, define pathological basis of imaging changes of glioma, and the relationship between CT perfusion parameters and glioma angiogenesis using a animal glioma mode.Objective:To observe perfusion parameter changes of tumor xenograft in C6 glioma rat at the different time points and at the different locations of tumors. To assesstumor angiogenesis features at the different time points and at the different locations after the implantation by comparing thickness and vessel diameter changes between the tumor neovascularity and host vessels, the changes of VEGF positive vascular endothelial cells, the relationship between VEGF expression and thickness and diameter of the vessel, the relationship between the CT perfusion parameters and VEGF expression in a rat C6 glioma model. To discuss the relationship between CT perfusion features and CT perfusion parameters during the different developmental stages of xenograft glioma; and to assess the feasibility of CT perfusion to diagnose glioma.To discuss angiogenesis features in the developmental process of glioma and pathological basis of infiltrative growth pattern of glioma, laying a foundation for the related experimental study and clinical management.Materials and Methods: 60 adult Wistar rats, with equal male to female ratio. They were randomly classified into 6 groups. Each group had 10 rats, corresponding to the 6 different time points of 5th day, 7th day, 10th day, 13th day, 15th day, 20th day. C6 glioma cell were cultured in the full medium (RP-1540) with 5% CO2 warm box, 37s attachment wall culture, pass generation into growth, and implant using cells in the logarithm growing stage. Inoculation procedure was made by using a rat stereotaxis, the targeting site was in the right cauda nuclei. Its coordinate is lmm prior to coronal suture, 3.0 mm at the parasagittal suture ,5.0mm at the depth of intradura. CT examination was performed in order at the different time points after the inoculation.Then pathological examinations were performed at the 6 time points following CT perfusion.CT examination was performed by using a multislice scanner (GE/lightspeed, GE Medical System). Contrast agent (Ultravist 300 ) was infused by tail vein of rat, with injection rate of 0.5ml/s, volume of 1.5ml/kg body weight. Brain tumor analysis software in the perfusion 3 was used to obtain cerebral blood flow (CBF), cerebral blood volume (CBV), permeability surface (PS) mapping in the centre of tumor, in the peripheral parts of tumors, in the borderline between the tumor and the adjacent tissue,and in the contralateral brain.Rats were sacrificed and cerebral tissue was removed, fixed by 4% formaldehyde, the specimen embedded by paraffin, HE staining performed. VEGF staining was made using a technique of SP according to the introductions in the reagent box.The measurement of microvessel diameter and mural thickness in the glioma: microvessel diameter and mural thickness were measured at the different location both in the capillary of normal brains and in the implanted gliomas using a pathological picture analysis system.Counting of VEGF positive vascular endothelial cells: VEGF positive vascular endothelial cells in the centre of tumor, in the peripheral parts of tumors, in the boundary area, and in the contrahemisphere were counted, respectilely.Compare the changes of BF, BF, PS at the different location (in the centre of tumor, in the peripheral parts of tumors, in the borderline between the tumor and the adjacent tissue, and in the contrahemisphere.),the changes of BF, BF, PS at the different time points (5d, 7d, lOd, 13d, 15d, 20d).Assess the relationship between VEGF expression and thickness and diameter of the vessel, the relationship between the CT perfusion parameters and VEGF expression in a rat C6 glioma model.Results:CT perfusion imaging: CBV, CBF, PS mapping could clearly display tumors. CT perfusion parameters in the areas of cystic changes and necrosis of tumors were lower, however, these parameters in the solid part of tumors were higher than those in the contrelateral brain parenchyma.Changes of CBF, CBV, and PS at the different time points:the changes of CBF, CBV, and PS between 5d and 7d, lOd and 13d,15d and 20d were different, combining the pathological changes of the gliomas, the developmental process of mouse C6 glioma could be classified into early, middle, and late stages. CT perfusion values in the peripheral part of the tumor were higher than that in the center of the tumor in the early and late stage of tumor. CT perfusion values in the peripheral part of the tumor weresimilar to that in the center of the tumor in the middle stage of tumor. At all stages CT perfusion value in the borderline area of the tumor were higher than that of contralaieral brain tissue, which had no obvious changes at all stages.CBF had a linear correlation with CBV at any stage,PS had a linear correlation with CBF and CBV in the early and middle stage of tumors,no correlation exists in the late stage of the tumor.Tumor vascular diameter and wall thickness were smaller than those in the contralateral on the 5th day, no statistical significance(p>0.05). After 7th day, tumor vascular diameter and wall thickness were larger than those in the contralateral brain, the tumor vascular diameter was 2-4 times of that in the contralateral brain, and vascular wall thickness is 2~6 times of that in the contralateral brain.There were no significant difference for vascular diameter between 5d and 7d,10d and 13d,15d and 20d(p>0.05).There was no significant difference between the central peripheral .boundary and contralateral brain at 5d and 7d,however ,there were difference between lOd and 13d,15d and 20d for the above locations(p<0.05).There were significant difference for vascular wall thickness in the cenrral,peripheral,and boundary part of the tumor in the early ,middle and late stage(p<0.05),however, no difference exeisted in the contralateral brain in the three differents stages(p>0.05).VEGF expression in the vascular walkVEGF staining in the peripheral part of tumor was stronger than that in the central in the early and late stages,having a significant difference(p<0.05).In the middle stage,VEGF staining in the peripheral part of tumor was similar to that in the central part,no difference existed(p>0.05).VEGF staining in the central and peripheral part of tumor in the middle stage was stronger than that in the late stage,however, VEGF expression in the boundary area was stronger than that in the contralateral brain in the late stage.At all stages there were significant difference between the different parts of the tumor and contralateral brain(p<0.05).In the early and middle stages, there were difference for VEGF expression in the central,peripheral part of tumor(p<0.05),however, there was no difference for the early and late stages(p>0.05);there was a difference in the boundary area of tumor(p<0.05).In the middle and late stages,there were significant difference for VEGF expression in the central and peripheral part of tumor(p<0.05),however,there was no difference for the boundary area(p>0.05).At all times points, the VEGF expression between the tumor central,peripheral,boundary and the contralateral brain had significant difference(p<0.05).There was a linear correlation between VEGF expression and vascular diameter,vascular wall thickness in the central part of the tumor in the early and middle stages.There was no any correlation in the late stage.They had correlation in the peripheral and boundary area of tumor and contralateral brain at all stages(p<0.05).In the early and middle stages,there were a linear correlation between VEGF expression and CBF,CBV and PS in the central part of the tumor,however,there was no any correlation in the late stage. They had correlation in the peripheral and boundary area of tumor and contralateral brain at all stages(p<0.05).Conclusions: We can draw the following conclusions through the comparison study between CT perfusion and pathology of C6 glioma.l.Rat C6 glioma is suituable to perform CT perfusion and angiogenesis study. The time point should be chosen as the early and middle stages (5th day to 15th day) for performing the related experimental study of angiogenesis (such as antiangiogenesis treatment and radiation therapy) using the C6 glioma model.2. There are difference between the vascular diameter and vascular wall thickness in the different locations of C6 glioma model.The reason of the increasement of CBFn CBVn PS in the center and peripheral of the glioma are vascular lumen enlargement and wall thicking rather than host vessel dilation.3.There is significant difference for the neovascular number at all stages.Angiogenesis is obvious in 5th day after transplantion of C6 glioma...
|
PDF Full Text Request