大鼠C6脑胶质瘤MR扩散加权成像及灌注成像与组织学对照研究

Usefulness of diffusion-weighted and perfusion-weighted MR in mouse C6 gliomas:correlation with histopathology

目的对大鼠脑胶质瘤MR扩散加权成像(DWI)及灌注成像(PWI)的实验研究,探讨两者在肿瘤生长及血管生成中的诊断价值。方法对36只颅内种植C6胶质瘤细胞的雌性Wistar大鼠分别于种植后1～4周行MRT1WI、T2WI、DWI、PWI及增强T1WI检查。处死后行脑组织HE及CD34免疫组织化学(简称免疫组化)染色。结果种植后3～4周,肿瘤实质区及肿瘤周围区表观扩散系数(ADC)值与种植后1～2周及对侧脑白质相比,差异均具有统计学意义(P<0.01)。胶质瘤实质区的ADC值随镜下肿瘤组织细胞构成比增加而降低,呈明显的负相关(r=-0.682,P<0.01)。种植后2～4周,肿瘤实质部分最大局部脑血容量(rCBVmax)与种植后1周及对侧脑白质相比,差异均具有统计学意义(P<0.01)。种植后1～2周,肿瘤周围区出现宿主血管rCBVmax值的增高,以种植后1周最为显著(t=3.88,P<0.01)。肿瘤实质区的rCBVmax值与CD34免疫组化微血管密度(MVD)计数值间具有显著的正相关(r=0.716,P<0.01)。结论DWIC6胶质瘤肿瘤实质区ADC值的减低与肿瘤恶性程度有关;C6胶质瘤的PWI肿瘤实质区rCBVmax值与组织学MVD值间具有显著的相关性,可作为1种活体评价肿瘤微血管的指标。肿瘤周围区rCBVmax值可对肿瘤的新生血管与正常脑组织原有血管扩张的鉴别有帮助。

Objective Diffusion/perfusion-weighted MRI (DWI、PWI) was performed to evaluate growth and vascularity of implanted C6 rat gliomas. Methods 36 female Wistar rats were implanted of C6 glioma cells intracerebrally. Between 1 and 4 weeks after implantation, eight to ten different rats were imaged with T_1WI, T_2Weighted imaging, DWI, PWI, and postcontrast T_1WI at each weekly time point. After MRI, each rat brain was examined histologically using HE and immunohistochemical staining for CD34. Results On DWIs, statistical differences of apparent diffusion coefficient (ADC) values for both the solid tumor component and peritumoral region were present comparing 3-4 weeks with 1-2 weeks after implantation (P<0.01). ADC value for the solid tumor component was negatively correlated with tumor cellularity (r=-0.682,P<0.01). Statistical difference of the maximal regional cerebral blood volume (rCBV_ max ) for the solid tumor components was present comparing 2-4 weeks with both 1-week after implantation and contralateral white matter (P<0.01). Native vessel dilation in regions of normal brain at the periphery of the tumors at 1 week after implantation was observed, and rCBV_ max in these regions were elevated compared to the contralateral sides (t=3.88,P<0.01). Prominent positive correlation was present between rCBV_ max of the solid tumor component and microvascular density (MVD) (r=0.716, P<0.01). Conclusion Reduced ADC value for the solid tumor component is correlated with malignancy of C6 gliomas. rCBV_ max for the solid tumor component can evaluate tumoral microvessel in vivo, while those at the periphery may be useful for the differentiation between native vessel dilation of normal brain and angiogenesis of the tumor.