【摘要】 目的 探讨何种b值扩散加权成像（DWI）对胶质瘤术前分级更有价值。方法 回顾性分析经手术病理证实的38例胶质瘤（高级别24例、低级别14例）患者的MRI资料,均行常规MRI检查和3种b值的DWI检查（b=1 000 s/mm²、2 000 s/mm²、3 000 s/mm²）,分析DWI上肿瘤的信号特征,测量肿瘤最小表观扩散系数（ADC）值。对不同b值的肿瘤最小ADC值绘制受试者工作特征曲线（ROC）,选取最佳诊断阈值,采用χ²检验分析不同序列的敏感性、特异性的差异。结果 b=3 000 s/mm² DWI图像上,91.6%（22/24）高级别胶质瘤呈高信号,85.7%（12/14）低级别胶质瘤呈低信号,以高信号作为诊断高级别胶质瘤的标准,诊断高级别和低级别胶质瘤的敏感性及特异性最高（91.6%和100%）。在b值相同时高级别胶质瘤的最小ADC值低于低级别胶质瘤,差异有统计学意义（P<0.05）;3种b值鉴别高级别和低级别胶质瘤敏感性的差异有统计学意义（P<0.05）,当以ADC 3 000<0.74×10^-3 mm²/s作为鉴别高级别胶质瘤的敏感性和特异性最高,分别为100%和87.3%。结论 高b值DWI比常规b值DWI更能准确反映胶质瘤分级,应用b=3 000 s/mm² DWI肿瘤最小ADC值为胶质瘤术前更准确分级提供量化指标。更多还原

【Abstract】 Objective To investigate the optimal b value of diffusion-weighted imaging（DWI） in predicting the grade of cerebral gliomas.Methods 38 patients with pathologically-proved brain gliomas（24 high-grade gliomas and 14 low-grade ones） were studied retrospectively.All patients received conventional MRI and DWI examination with three different b values（1 000 s/mm²,2 000 s/mm² and3 000 s/mm²）.The signal features of the tumor on DWI with three different b values were evaluated and compared.The minimum ADC values of the tumors were calculated and compared between each other.Through drawing the ROC curve of different b values,the best diagnostic threshold was found.The sensitivity and specificity in predicting the grade of brain gliomas were assessed using Chi-square test.Results On DWI with b value of 3 000 s/mm²,91.6%（22/24） of high-grade tumors showed hyper-intensity,while85.7%（12/14） of low-grade tumors presented hypo-intensity signals.Regarding hyper-intensity signals as diagnostic criterion for high-grade tumors,the sensitivity and specificity were 91.6% and 100% respectively.When the b value was similar,the minimum ADC value of high-grade glioma was significantly lower than that of low-grade glioma,and statistically significant differences in differentiating high-grade glioma from low-grade glioma existed among three b values（P<0.05）.When the ADC 3 000 value<0.74×10^-3 mm²/s was regarded as a standard for the identification of high-grade and low-grade glioma,the sensitivity and specificity were 100% and 87.3%respectively.Conclusion DWI with high b value is more useful than standard moderate b value in preoperative grading the gliomas.When DWI with b value of 3 000 s/mm² is used,the minimum ADC value will provide quantitative indicators in preoperatively precisely predicting grading glioma.更多还原