MR扩散加权成像对桥小脑角区实性神经鞘瘤与脑膜瘤的鉴别诊断价值

目的：探讨 MR扩散加权成像(DWI)及表观扩散系数(ADC)在桥小脑角区实性神经鞘瘤与脑膜瘤鉴别诊断中的价值。方法回顾性分析经术后病理证实的桥小脑角区12例实性神经鞘瘤和27例脑膜瘤的 DWI 图像,逐层勾画肿瘤边界以获得整体感兴趣区(ROI),得到肿瘤的平均 ADC 值(mADC)。同时以脑干 mADC 值为参考,计算得到肿瘤/脑干 ADC 比值(ADC ratio, rADC=肿瘤 mADC值/脑干 mADC值)。桥小脑角区实性神经鞘瘤和脑膜瘤之间的 mADC 和 rADC 值差异采用独立样本t检验分析。采用受试者工作特征曲线(ROC)分析 mADC 和 rADC 值在两者鉴别诊断中的价值。结果桥小脑角区实性神经鞘瘤mADC和 rADC值均明显高于脑膜瘤(mADC,P=0.001；rADC,P=0.002)。以 mADC=0.994×10-3 mm2/s 作为诊断阈值,鉴别实性神经鞘瘤和脑膜瘤的价值最优曲线下面积(AUC)0.917；敏感度92%；特异度89%]。结论 MR DWI对桥小脑角区实性神经鞘瘤与脑膜瘤的鉴别诊断有一定的参考价值。

The value of MR diffusion weighted imaging in differentiating solid schwannoma and meningioma of cerebellopontine angle

Objective To evaluate the value of diffusion weighted imaging (DWI)and apparent diffusion coefficient (ADC)in differentiating solid schwannoma and meningioma located in cerebellopontine angle.Methods DWI data of 12 patients with solid schwannoma and 27 patients with meningioma confirmed by postoperative pathology were analyzed retrospectively.Tumor was described carefully slice by slice as the whole region of the interest (ROI)to measure mean ADC value (mADC).ADC ratio (rADC)was calculated as mADC of tumor divided by mADC of brain stem.mADC and rADC were compared between the solid schwannoma and meningioma by using independent-samples t test. The receiver operating characteristic (ROC)curve was used to evaluate the value of mADC and rADC in differentiating solid schwannoma and meningioma.Results mADC and rADC values of the solid schwannoma were significantly higher than those of the meningioma (mADC,P=0.001;rADC,P=0.002,respectively).The optimal diagnostic performance was achieved if 0.994×10-3 mm2/s was set as the cutoff value of mADC in differentiating solid schwannoma and meningioma (AUC 0.917;sensitivity 92%;specificity 89%).Conclusion MR DWI is helpful to differentiate solid schwannoma and meningioma in cerebellopontine angle.