ADC值鉴别肺部良恶性病变的价值及b值的优化

目的探讨DWI表观扩散系数（apparent diffusion coefficient,ADC）值对鉴别肺部艮、恶性病变的价值及b值优化。方法对82例肺部结节或肿块行常规MRI和DwI检查，分别测量b值为300、500、800s／mm2时的病变ADC值。比较同-b值下良、恶性病变ADC值的差异。根据受试者工作特征曲线（receiveoPeratingcharacteristiccurve，ROC）评价不同b值下ADC值鉴别肺部良恶性病变的诊断效能。结幕82个病例中恶性病变54例，艮性病变28例。不同b值下恶性病变的平均AD均值均明显小于良性病变平均ADC值，差异均有统计学意义（P均〈0．05）。b值取300、500、800S／mm2，AuC分别为0．806，0．838，0．826，均有诊断意义（AUC〉0．5）：其中b=500s／mm2。时ADc值诊断效能最高，ADC阂值为1．492×10-3mm2／S，其敏感度、特异度、准确度分别为88．9％、78．6％、85．92％。结论ADC值有助于鉴别肺部良恶病变，b值取500S／mm2时诊断效能较高。

Value of Identifying benign and Malignant Lung Lesions With ADC Value and Opti- mizing b Value

Objective To evaluate the value of identifying benign and malignant lung lesions with apparent diffusion coefficient （ADC） value and to optimize b value. Methods Eight- two pulmonary lesions patients underwent conventional MRI and DWI. ADC values of the lesions were measured with b=300s/mm2. 500s/mm2 and 800s/ram2, respectively. ADC values of benign and malignant lesions at the same h value were compared.Area under the receive operating characteristic curve （ROC） with the various b values were ascertained the diagnostic efficiency of identifying benign and malignant lung lesions With ADC value. Results In 82 cases, 54 lesions were malignant, 24 were benign. The mean ADC values of malignant lesions were lower than that of benign lesions with various b values（all P 〈 0. 01）. The AUC with various b values was 0.806, 0.838, 0.826, respectively. The diagnostic efficiency was the highest when the b value was 500s/mm2 and the threshold of ADC value was 1.492× 10^3mm2/s. Sensitivity, specificity, accuracy in differential diagnosis of be- nign and malignant lung lesions were 88.9%, 78.6%, 85.92% respectively. Conclusion Mean ADC value can be used to distinguish benign and malignant pulmonary disease with various b values （300, 500 and 800s/mm2）. And, the diagnostic efficiency is the highest when b value was 500s/mm2） .