【作者】 李波；

【导师】 徐海波；

【作者基本信息】 武汉大学 ， 影像医学与核医学， 2022， 博士

【摘要】 目的:准确监测肿瘤血管正常化进程有利于患者的精准治疗。目前缺乏安全、无创的监测方法。通过体素内不相干运动扩散加权成像(intra-voxel incoherent motion diffusion weighted imaging,IVIM-DWI)和组织病理学方法连续监测肿瘤抗血管生成治疗的血管正常化时间窗,验证IVIM-DWI监测肿瘤血管正常化时间窗的可行性。方法:共建立了60只大鼠C6原位异种移植胶质瘤模型(50只用于IVIM-DWI成像及组织病理监测,10只用于电镜观察)。第一部分:将50只大鼠随机平均分为5个对照组和5个贝伐单抗治疗组。每组随机选取5只大鼠在5个不同时间点(治疗后第0、2、4、6、8天)进行MR扫描,使用西门子3T超导磁共振扫描如下序列:快速自旋回波序列T1加权成像(T1 weighted imaging,T1WI)、T2加权成像(T2 weighted imaging,T2WI)和自旋回波平面成像序列IVIM-DWI。并获得IVIM-DWI定量参数:灌注分数(perfusion fraction,f)、真弥散系数(true diffusion coefficient,D)、伪弥散系数(pseudo-diffusion coefficient,D*)、f D*。每个时间点MRI完成后获取脑肿瘤组织,评估微血管密度(microvessel density,MVD)、周细胞覆盖率和缺氧诱导因子-1α(hypoxia-inducible factor-1α,HIF-1α)等病理指标。第二部分:将10只大鼠随机平均分为5个对照组和5个贝伐单抗治疗组。每组随机选取1只大鼠在5个不同时间点(治疗后第0、2、4、6、8天)获取脑组织后电子显微镜观察肿瘤血管结构变化。单因素方差分析和t检验用于比较组内和组间的差异。Spearman相关系数(r)评估IVIM与病理参数之间的相关性。组内相关系数(intra-group correlation coefficient,ICC)评估每个IVIM参数的可重复性。结果:(1)贝伐单抗治疗组及对照组各组肿瘤体积在基线时(干预后第0天)差异无统计学意义(P>0.05)。在第6天、第8天对照组肿瘤体积明显大于治疗组(P<0.05)。(2)治疗组f值在第2、4和6天高于对照组(P<0.05),第4天差异最大;与基线相比,治疗组f值在第2天和第4天升高(P<0.05)。在第2天治疗组D值较对照组升高(P<0.05);治疗组其他各时间点的D值与基线相比不存在统计学差异(P>0.05)。在第4天治疗组D*值明显高于对照组(P<0.05);治疗组其他各时间点的D*值与基线之间不存在统计学差异(P>0.05)。在第2天和第4天治疗组f D*值高于对照组(P<0.05);与基线相比,治疗组的f D*值在第4天升高(P<0.05)。(3)干预后第2天,治疗组MVD低于对照组(P<0.05)。干预后第4天,治疗组周细胞覆盖率明显高于对照组(P<0.05)。治疗组和对照组之间HIF-1α未观察到统计学差异(P>0.05)。(4)在对照组中,f与MVD的相关性最高(r=0.689),其次是f D*(r=0.594);D*及D与微血管密度无明显相关性。周细胞覆盖率与f D*轻度正相关(r=0.398),其次为f(r=0.338),D*及D与周细胞覆盖率无明显相关性。HIF-1α与IVIM各参数之间无明显相关性。在治疗组中,f与MVD的相关性最高(r=0.602),其次是f D*(r=0.552)和D*(r=0.416);D与MVD无明显相关性。周细胞覆盖率与f呈中等程度相关(r=0.557),其次是f D*(r=0.394)和D*(r=0.318),D与周细胞覆盖率无明显相关性。HIF-1α与f(r=0.480)和f D*(r=0.447)呈中等程度正相关,其次是D*(r=0.335),而D与其无明显相关性。(5)对照组的D*值的可重复性一般,对照组其他参数均具有良好的可重复性。治疗组的所有参数均显示出良好的可重复性。(6)电镜显示治疗组的内皮细胞间紧密连接在第2-4天延长、无裂隙,基底膜连续完整,内皮细胞形态多扁平,胞饮小泡少;治疗组其他时间点及对照组各时间点电镜显示内皮细胞间紧密连接不完整且裂隙增多,基底膜不连续,部分内皮细胞形态饱满,胞饮小泡较多。结论:贝伐单抗治疗胶质瘤的血管正常化时间窗为抗血管生成治疗后2-4天,可通过IVIM-DWI无创监测。IVIM-DWI参数与病理参数间存在相关性。更多还原

【Abstract】 Objective Accurate monitoring of tumor blood vessel normalization progression is beneficial to accurate treatment of patients.At present,there is a lack of safe and non-invasive monitoring methods.To serial monitor the vascular normalization time window of tumor anti-angiogenesis treatment through intra-voxel incoherent motion diffusion-weighted imaging(IVIM-DWI)and histopathological methods,verify the feasibility of IVIM-DWI monitoring the vascular normalization time window of tumor.Methods A total of 60 rat C6 in situ Xenograft glioma models were established(50for magnetic resonance imaging(MRI)and 10 for electron microscope testing).In the first part,these 50 rats were randomly and equally divided into the five control groups and five bevacizumab treatment groups.Five rats in each group were randomly selected for MR scan at five different time points(days 0,2,4,6,and 8 after treatment),and the IVIM-DWI quantitative parameters(f,D,D*,and f D*)were obtained.The following sequences were scanned using Siemens 3T superconducting magnetic resonance imaging: T1 weighted imaging(T1WI),T2 WI with a fast spin echo sequence and IVIM-DWI with a spin-echo echo-planar imaging sequence.After MRI,the brain tumor tissues were monitored to assess the pathological indicators of microvessel density(MVD),pericyte coverage,and hypoxia-inducible factor-1α(HIF-1α).In the second part,10 rats were randomly divided into 5 control groups and5 bevacizumab treated groups.One rat in each group was randomly selected at 5different time points(days 0,2,4,6,and 8 after treatment)to obtain brain tissue for electron microscope observed changes in tumor vascular structure.One-way analysis of variance(ANOVA)and Student’s t-tests were used to compare differences within and between groups.Spearman’s correlation coefficient(r)assess the correlation between IVIM and pathological parameters.The intra-group correlation coefficient(ICC)was determined to assess the repeatability of each IVIM parameter.Results(1)There was no significant difference in tumor volume between the bevacizumab treatment group and the control group at baseline(day 0 after intervention)(P>0.05).The tumor volume in the control group was significantly larger than that in the treatment group on days 6-8(P<0.05).(2)The f value of the treatment group was higher than that of the control group on the day 2,day 4 and day6(P<0.05),and the difference was the largest on the day4;compared with the baseline,the f value of the treatment group increased on the day 2 and day 4(P<0.05).On the day 2,the D value of the treatment group was higher than that of the control group(P<0.05);the D value of the treatment group at other time points was not significantly different from the baseline(P>0.05).On the day 4,the D* value in the treatment group was significantly higher than that in the control group(P<0.05);there was no statistical difference between the D* value at other time points in the treatment group and the baseline(P>0.05).The f D* value of the treatment group was higher than that of the control group on days 2 and 4(P<0.05);compared with baseline,the f D* value of the treatment group was increased on day 4(P<0.05).(3)On the 2 days after the intervention,the microvessel density(MVD)of the treatment group was lower than that of the control group(P<0.05).On the 4 days after intervention,the pericyte coverage rate in the treatment group was significantly higher than that in the control group(P<0.05).No statistical difference was observed in hypoxia-inducible factor-1α(HIF-1α)between the treatment group and the control group(P>0.05).(4)In the control group,f had the highest correlation with MVD(r=0.689),followed by f D*(r=0.594);D* and D had no significant correlation with microvessel density.Pericyte coverage was slightly positively correlated with f D*(r=0.398),followed by f(r=0.338).D* and D had no significant correlation with pericyte coverage.There was no significant correlation between HIF-1α and IVIM parameters.Among the treatment groups,f had the highest correlation with MVD(r=0.602),followed by f D*(r=0.552)and D*(r=0.416);D had no significant correlation with MVD.Pericyte coverage was moderately correlated with f(r = 0.557),followed by f D*(r=0.394)and D*(r=0.318),and D had no significant correlation with pericyte coverage.HIF-1αwas moderately positively correlated with f(r=0.480)and f D*(r=0.447),followed by D*(r=0.335),but D had no significant correlation with it.(5)The repeatability of the D* value of the control group is general,and other parameters of the control group have good repeatability.All parameters of the treatment groups showed good reproducibility.(6)Electron microscope showed that the tight junctions between endothelial cells in the treatment group were prolonged and had no fissures on days2-4,the basement membrane was continuous and intact,the shape of endothelial cells was mostly flat,and there were few pinocytosis vesicles;other time points in the treatment group and control group were Time-point electron microscopy showed that the tight junctions between endothelial cells were incomplete and the number of fissures was increased,the basement membrane was discontinuous,some endothelial cells were plump in shape,and there were many pinocytosis vesicles.Conclusion The vascular normalization time window of bevacizumab treatment of glioma was days 2-4 after anti-angiogenesis treatment,which could be monitored non-invasively by IVIM-DWI.There was a correlation between IVIM-DWI parameters and pathological parameters.更多还原