体素内不相干运动扩散加权成像在良性脑膜瘤中的初步研究

目的 探讨多b值体素内不相干运动扩散加权磁共振成像（introvoxel incoherent motion MR imaging,IVIM MRI）的单、双指数模型在良性脑膜瘤中的应用价值.方法 纳入22例手术病理证实为良性脑膜瘤并术前行常规MR序列及IVIM序列扫描的患者.多b值IVIM序列包括14个b值（0～1 000s/mm2）,所得IVIM序列原始数据经单、双指数模型处理,得到单、双指数模型衰减曲线,并生成对应参数图,测量肿瘤实质区及正常脑白质的单指数模型的扩散系数ADC值和双指数模型的扩散系数D值、灌注分数f值、灌注系数D＊值,采用配对样本t检验进行统计学分析.结果 单、双指数模型衰减曲线显示肿瘤实质区信号强度随b值的增大而衰减.肿瘤实质区ADC值、D值、D＊值、f值分别为（0.87±0.13）μm2/ms、（0.79±0.10）μm2/ms、（58.68±27.52）μm2/ms、（7.68±3.59）％;正常脑白质的ADC值、D值、D＊值、f值分别为（0.74±0.06）μm2/ms、（0.69±0.04）μm2/ms、（93.43±31.64）μm2/ms、（4.48±2.39）％.单指数模型中肿瘤实质区ADC值较正常脑白质ADC值两者比较差异有统计学意义（t=5.793,P＜0.05）;双指数模型中,肿瘤实质与正常脑白质D、f、D＊值分别进行比较,肿瘤实质的D、f值均较正常脑白质增高（t=4.384,P＜0.05和t=3.349,P＜0.05）;而肿瘤实质D＊值较正常脑白质D＊值减低（t=-3.559,P＜0.05）.肿瘤实质区单指数模型ADC值与双指数模型D值两者差异有统计学意义,且单指数ADC值显著较双指数模型D高（t=6.492,P＜0.05）.结论 基于棠规DWI序列的多b值IVIM双指数模型可以更准确地描述良性脑膜瘤的扩散信息,同时非侵入性地获得肿瘤灌注信息.

The pilot study of benign meningiomas using intravoxel incoherent motion imaging

Objective To evaluate the diagnostic performance of monoexponential model and the bi-exponential modeling of intravoxel incoherent motion （IVIM） MR imaging for benign meningiomas in brain.Methods All patients in this study provided written informed consent to the scanning.Twenty-two patients with histologically proven benign meningiomas were examined on a 3.0T MR seanners（Achieva 3.0 T TX,Philips,The Netherlands）.The scanning protocol included the conventional MR imaging,IVIM MR imaging and contrast-enhanced MR imaging.The IVIM sequence was performed with 14b values between 0 and 1 000 s/mm2 on 3 orthogonal directions.Region-of-interest was manually set on the tumor as well as in the normal white matter.All the data were fitted by a monoexponential model [yielding the apparent diffusion coefficient （ADC）] and the bi-exponential model （yielding the diffusion constant D,the pseudodiffusion coefficient of perfusion D ＊ and the perfusion fraction f）.The paired t tests were used to assess differences between the tumor and normal white-matter.Results Signal decay curves were bi-exponential in the benign meningiomas.The ADC,D,D＊ and f values of benign meningiomas were （0.87±0.13） μm2/ms,（0.79±0.10） μm2/ms,（58.68±27.52） μm2/ms,（7.68±3.59）％ and those values of the normal white-matter were （0.74±0.06） μm2/ms,（0.69±0.04） μm2/ms,（93.43±31.64） μm2/ ms,（4.48±2.39） ％,respectively.The differences of the ADC,D,D＊ and f values between two groups were statistically significant （t =5.793,4.384,-3.559,3.349; P ＜0.05,respectively）.The differences of the ADC and the D values between the benign meningiomas parenchyma were statistically significant （t =0.579,P ＜0.05）.Conclusion IVIM imaging might be a valid and promising method to quantify perfusion and more accurate diffusion in benign meningiomas.