磁共振常规成像及DWI对脑膜瘤的诊断价值

The diagnostic value of conventional MRI and DWI for meningioma

目的:比较磁共振常规成像序列(T1WI、T2WI及FLAIR)与DWI对脑膜瘤的检出率,探讨其鉴别病理亚型及良恶性的价值。方法:回顾性分析70例经手术病理证实的脑膜瘤患者的MRI图像,计算不同序列对脑膜瘤的检出率;测量并比较不同病理亚型、不同病理分级的肿瘤实质的平均ADC值和相对ADC值(rADC值)。结果:在T2WI上出现低信号的多是纤维型、过渡型和砂粒体型,出现高信号的多是脑膜上皮型和血管瘤型。在各个序列中,以DWI对脑膜瘤病变的检出率最高(87.1%),T2WI次之(74.3%),T1WI最低(38.6%)。恶性脑膜瘤的囊变发生率(67%)明显高于良性脑膜瘤(22%)。良性组各亚型间、良恶性两组间平均ADC值及rADC值差异均无统计学意义(P>0.05)。结论:DWI可提高对脑膜瘤的检出率,但单独根据ADC值并不能鉴别脑膜瘤的亚型及良恶性。DWI结合常规MRI表现对脑膜瘤亚型及良恶性的鉴别有一定意义。

Objective：To explore the value of conventional MRI sequence（including T1/T2 weighted imaging and fluid-attenuated inversion-recovery（FLAIR）） and diffusion weighted imaging（DWI） in detecting meningioma and judging its subtypes and malignancy.Methods：The MR images（including T1WI,T2WI,FLAIR and DWI） of 70 meningioma cases confirmed by surgery and pathology were retrospectively analyzed.Detection rate of each series was obtained based on the signal change of meningioma.The apparent diffusion coefficient（ADC） and relative ADC（rADC） of the substantial part of tumor were measured and compared among different subtypes and between benign and malignant meningiomas.Results：On T2WI hypointense tumors were mostly fibrious,transitional or psammomatous meningiomas;and hyperintense tumors were mostly found in meningothelial or angiomatous meningiomas.Among all these sequences the detection rate of DWI was significantly higher than others.The incidence of intra-tumoral cystic change in malignant meningioma（67%） was significantly higher than that of benign meningioma（22%）.However,there was no significant difference of ADC or rADC between benign and malignant meningiomas.Conclusion：DWI is able to assist the detection of meningioma,however,the ADC alone could not classify meningioma subtypes.Combining conventional MRI and DWI may be useful in judging the subtype and malignancy of meningioma.