体素内不相干运动扩散加权成像在鉴别肺部良恶性病变中的价值

The Value of Intravoxel Incoherent Motion Diffusion-weighted Imagingin Distinguishing Benign and Malignant Lung Lesions

目的:探讨磁共振体素内不相干运动扩散加权成像(IVIM-DWI)单指数模型参数及ADC值在鉴别肺部良恶病变中的诊断价值。方法:收集经病理证实的肺部病变45例,其中恶性30例,良性15例,所有患者术前或治疗前均行IVIM-DWI及单b值DWI检查,b值取0、10、25、50、100、200、400、600、800、1000s/mm2,分别测量所有病灶的真实扩散系数D值、灌注相关扩散系数D*值、灌注分数f值;单b值取600s/mm2测量ADC值,分别对肺部良恶性病变的4个参数进行分析,并绘制ROC曲线评价各值的诊断效能。结果:肺部良性病变组ADC值(1.748±0.329)×10-3mm2/s,明显高于肺部恶性病变组ADC值(1.323±0.448)×10-3mm2/s,差异有统计学意义;肺部良性病变组D值(1.328±0.295)×10-3mm2/s,明显高于肺部恶性病变组D值(0.812±0.214)×10-3mm2/s,差异有统计学意义;而D*值、f值两组间差异无统计学意义。D值与ADC值的ROC曲线下面积分别为0.930与0.805,两者的敏感性、特异性分别是0.944与0.889、0.750与0.667。结论:IVIM-DWI单指数模型参数D值及ADC值均对肺部良恶性病变的诊断与鉴别诊断具有重要价值,且D值的诊断效能较ADC值高。

Purpose： To study the value of intravoxel incoherent motion （IVIM） and apparent diffusion coefficient （ADC） of MRI diffusion weighted imaging （DWI） in differentiating benign and malignant lung lesions. Methods： Forty-five patients with lung masses were included： 30 cases were malignant and 15 cases were benign. Patients were imaged with 3.0T MRI DWI using 10 b-values, which was 0, 10, 25, 50, 100, 200, 400, 600, 800, 1000s/mm^2, respectively, and single b-value, which was 600s/mm^2. Tissue diffusivity （D）, pseudo-diffusion coefficient （D＊）, and perfusion fraction （f） were calculated using bi-exponential model analysis. And ADC values were compared between benign and malignant lung lesions. Receiver operating characteristic （ROC） analysis was performed for all DWI parameters. Results： The ADC value was significantly higher for benign lesions than that for malignant lung lesions （[ 1.748±0.329]×10^-3mm^2/s vs. [ 1.323±0.448] ×10^-3mm^2/s; P=-0.007）. By IVIM, D value was significantly higher for benign lesions than that for malignant lung lesions （[1.328±0.295]×10^-3mm^2/s vs. [0.812±0.214]×10^-3mm^2/s; P=0.001）. There was no difference in D^＊ value and f value between benign and malignant lung lesions （P=-0.427 and 0.301, respectively）. D value showed comparable diagnostic performance with ADC in differentiating benign lung lesions from malignant lung lesions, with areas under the curve 0.930 and 0.805, sensitivity 0.944 and 0.889, and specificity 0.750 and 0.667, respectively. Conclusion： The IVIM parameter D value can provide comparable diagnostic performance with ADC and could be used as a surrogate marker for differentiating benign and malignant lung lesions. The diagnosis efficiency of the D value is higher than that of the ADC value.