DCE-MRI定量参数与脑胶质瘤Ki-67标记指数的相关性分析

Correlation of Ki-67 labeling index with quantitative dynamic contrast-enhanced MRI in glioma

目的:探讨磁共振动态对比增强扫描(DCE-MRI)定量参数预测脑胶质瘤细胞增殖的价值。方法:回顾性分析经病理证实的40例脑胶质瘤患者的病例资料,其中WHOⅡ～Ⅳ级胶质分别为18、7和15例。所有肿瘤术后均行Ki-67指数免疫组化检测,所有患者在术前行常规平扫及DCE-MRI扫描,经后处理软件分析获得肿瘤的DCE-MRI定量参数值,包括容积转运常数(K_(trans))、血管外细胞外容积分数(V_e)、速率常数(K_(ep))和血浆容积分数(V_p)共四项渗透相关参数,及脑血流量(CBF)和脑血容量(CBV)两项灌注参数,计算相对脑血流量(rCBF)和相对脑血容量(rCBV)。采用两独立样本t检验比较各参数在高级别和低级别胶质瘤之间的差异,并对各参数与Ki-67指数进行Spearman相关性分析。结果:高级别胶质瘤组的各项DCE-MRI参数值及Ki-67指数均高于低级别胶质瘤组,差异在两组间有统计学意义(P<0.05);K_(trans)、V_e、rCBV和rCBF值与Ki-67指数呈正相关(r=0.742、0.636、0.642、0.633,P<0.001),K_(ep)值与Ki-67指数亦呈正相关(r=0.490,P=0.002),V_p值与Ki-67指数间无显著相关性(r=0.238,P=0.145)。结论:DCE-MRI定量参数均可评估胶质瘤的病理分级,其中K_(trans)、V_e、K_(ep)、rCBV和rCBF值与Ki-67指数呈正相关,可作为术前评估胶质瘤细胞增殖程度的指标。

Objective: The purpose of this study was to explore the value of quantitative parameters of dynamic contrast-enhanced MRI for tumor cell proliferation in glioma. Methods: The medical data of 40 patients with glioma (18 with WHO-Ⅱ grade,7 with WHO-Ⅲ grade and 15 with WHO-Ⅳ grade) and the Ki-67 labeling index obtained by immunohistochemical detection in post-operative pathology were retrospectively analyzed.All patients were scanned at a 3.0T MRI system using T 1WI,T 2WI,T 2-FLAIR and dynamic contrast enhanced (DCE) sequence.DCE-MRI parameters,including volume transfer constant (K trans ),fractional volume of the extravascular to extracellular space (V e),fractional volume of the intravascular compartment (V p),the rate constant (K ep ),cerebral blood flow (CBF) and cerebral blood volume (CBV),were measured and analyzed in different grades.Relative CBV (rCBV) and CBF (rCBF) were calculated based on normalized mirror regions.T-test of two independent samples was used to analyze the statistical difference of each parameter mentioned above between different grades.The correlation of DCE-MRI quantitative parameters with Ki-67 labeling index (LI) were analyzed using the Spearman correlation test. Results: All quantitative parameters from DCE-MRI and Ki-67 LI were statistically different between the high-grade group and low-grade group ( P <0.05).The K trans ,V e,rCBV and rCBF values associated with Ki-67 LI ( r =0.742,0.636,0.642 and 0.633,P <0.001).The K ep value was also associated with Ki-67 LI ( r =0.490,P =0.002).The V p value was not associated with Ki-67 LI ( r =0.238,P =0.145). Conclusion: All the quantitative parameters from DCE-MRI are useful to differentiate low-grade from high-grade gliomas.The K trans ,V e,K ep ,rCBV and rCBF values significantly correlated with Ki-67 LI respectively,thus can be used as non-invasive indexes for prediction of cell proliferation in glioma before surgery.