MRI弥散加权成像表观扩散系数在低、高级别脑膜瘤鉴别诊断中的应用

Application of apparent diffusion coefficient of MRI diffusion-weighted imaging in the differential diagnosis of low-and high-grade meningiomas

目的探讨常规MRI结合弥散加权成像(DWI)中表观扩散系数(ADC)在低、高级别脑膜瘤的鉴别诊断中的临床应用价值。方法回顾性分析中国科学技术大学附属第一医院2018年1月—2019年8月68例脑膜瘤患者的临床资料,男29例、女39例,年龄24~78(48.62±10.28)岁。其中WHOⅠ级脑膜瘤52例(低级别组),WHO Ⅱ级12例、WHO Ⅲ级4例(高级别组)。患者术前均行常规MRI结合DWI检查。观察两组患者的MRI征象以及DWI特点;比较两组患者脑膜瘤实质和瘤周水肿部位ADC值以及肿瘤实质与对侧脑白质的相对表观扩散系数(rADC),利用ROC曲线分析最佳rADC值对低、高级别脑膜瘤的诊断效能。结果两组患者基线资料差异均无统计学意义(P值均>0.05)。高级别组脑膜瘤边缘不规整、强化不均匀、边缘水肿区、脑膜尾征和囊变、坏死、钙化区等影像学征象发生率明显高于低级别组脑膜瘤,差异均有统计学差异(P值均<0.05)。52例低级别组脑膜瘤中,有38例DWI、ADC均呈等信号,14例DWI呈稍高信号、ADC呈稍低信号;16例高级别组脑膜瘤实质部分DWI呈高信号、ADC呈低信号,而囊变、出血坏死、钙化区呈高信号。低级别组、高级别组脑膜瘤肿瘤实质部分ADC值分别为(0.94±0.14)×10^-3、(0.73±0.11)×10^-3 mm^2/s,rADC值分别为(1.16±0.18)×10^-3、(0.95±0.14)×10^-3 mm^2/s,低级别组脑膜瘤实质部分ADC和rADC值均明显高于高级别组脑膜瘤,差异均有统计学意义(t=5.491、4.277,P值均<0.01);低级别组、高级别组脑膜瘤的瘤周水肿区域ADC分别为(1.82±0.19)×10^-3、(1.88±0.21)×10^-3 mm^2/s,rADC值分别为(2.29±0.24)×10^-3、(2.38±0.29)×10^-3 mm^2/s,差异均无统计学意义(P值均>0.05);以rADC值诊断低级别组、高级别组脑膜瘤的最佳临界点为1.035×10^-3 mm^2/s,其灵敏度为88.5%,特异度为87.5%。结论常规MRI结合DWI中ADC值的测量对低、高级别脑膜瘤的鉴别诊断具有重要临床应用价值。

Objective This work aims to explore the clinical value of conventional MRI combined with apparent diffusion coefficient(ADC)in the differential diagnosis of low-and high-grade meningiomas.Methods Retrospective analysis was conducted on clinical data obtained from 68 patients with meningioma[(29 males and 39 females,aged 24-78(48.62±10.28)years]in the First Affiliated Hospital of the University of Science and Technology of China from January 2018 to August 2019.Among these patients,52 had WHO gradeⅠmeningioma(low grade group),12 had WHO gradeⅡ,and 4 had WHO gradeⅢ(high grade group).All patients underwent routine MRI and diffusion weighted imaging(DWI)examination prior to their operation.Comparison of MRI signs,diffusion-weighted imaging characteristics,ADC values of meningioma parenchyma and peritumoral edema,and relative apparent diffusion coefficient(rADC)of tumor parenchyma and contralateral white matter was conducted between the two groups.Receiver operating characteristic(ROC)curve was used to analyze the diagnostic efficacy of best rADC values for low-and high-grade meningiomas.Results No statistical difference was found in the baseline data of the two groups(all P values>0.05).High-grade meningioma presents a high occurrence frequency of these imaging signs,such as irregularity on tumor edge,uneven enhancement,marginal edema,meningeal tail and cyst changes,necrosis,and calcification,and the differences reached a statistical significance(all P values<0.05).Among the cases of low-grade meningioma,32 showed equal signals on DWI and ADC,and 14 showed slightly high signal on DWI and slightly low signal on ADC.Sixteen cases of high-grade meningioma showed high signal on DWI,cystic changes,hemorrhagic necrosis,and calcified areas but low signal on ADC.The ADC and rADC values of the parenchyma of low-grade meningioma were(0.94±0.14)×10^-3 and(1.16±0.18)×10^-3 mm^2/s,respectively,which were significantly higher than those of high-grade meningioma at(0.73±0.11)×10^-3 and(0.95±0.14)×10^-3 mm^2/s,respectively,and the differences were statistically significant(t=5.491,4.277,all P values<0.01).The ADC and rADC values of the peritumoral edema area of low-grade meningioma were(1.82±0.19)×10^-3 and(2.29±0.24)×10^-3 mm^2/s,respectively,those of high-grade meningioma were(1.88±0.21)×10^-3 and(2.38±0.29)×10^-3 mm^2/s,respectively,no significant differences were observed between two groups(all P values>0.05).The best critical points for diagnosing low-and high-grade meningiomas were rADC value of 1.035×10^-3 mm^2/s,sensitivity of 88.5%,and a specificity of 87.5%.Conclusions Conventional MRI combined with DWI ADC value has important clinical value for the differential diagnosis of low-and high-grade meningiomas.