表观弥散系数对肺部良恶性病变的鉴别价值

The Value on Distinguishing Pulmonary Benign and Malignant Lesions by ADC Values

目的探讨表观弥散系数（apparentdiffusioncoefficient，ADC）对肺部良、恶性肿块的鉴别诊断价值，并寻找最佳b值及阈值。方法经临床、穿刺或手术病理证实的58例良性病变和50例恶性病变，行MRI常规T1、T2和DWI扫描（b值为0、500、800、1000s／mm^2），其中2例DWI仅于b=800s／mm^2扫描;对DWI上显示高信号的良恶性病灶分别测量并比较不同b值的ADC值及其鉴别诊断效能，从中选择最佳b值，用t检验和受试者操作特征曲线（receiveoperationcharacteristiccurve，ROC）比较并评价该b值ADC值鉴别诊断肺部良恶性病灶的敏感性、特异性、准确性。结果50例良性病变可见高信号，48例恶性病灶显示高信号，两者略有差异（P=0．08），其中不同b值下49例良性和47例恶性病变组平均ADC值均随b值增加逐渐变小，差异有统计学意义（F=7．609，P=0．001；F=7．045，P=0．001）。三种b值ROC曲线下面积均有诊断意义（Az〉0．5），且以b取800s／mm^2时获得的ADC值诊断效能最大，该b值下恶性病变的ADC值[（1．07±0．23）×10^-2mm^2／s]明显低于良性病变[（1．88±0．41）×10^-3mm^2／s]，（t=11．978，P=0．000〈0．01），以ADC值为1．380×10^-3mm^2／s作为良恶性病变鉴别诊断的阈值，其敏感度、特异度和准确度分别为97．90％、88．00％和93．87％。结论ADC值可作为鉴别肺部良恶性肿块的有效指标。

Objective To evaluate the ADC vaine in differentiating the malignant from benign pulmonary lesions, and to explore the optimal b value and the diagnostic threshold of the ADC. Methods 58 benign lesions and 50 malignant lesions with proved lung tumors underwent MRI and DWI Co value： 0,500,800 and 1000 s/mm^2）,and different ADCs were generated. 2 patients were only underwent MRI and DWI （b value： 0, 800 s/mm^2）. Results 50 benign lesions and 48 malignant lesions were visible in DWI, and visibility of benign nodules was lower than that of malignant tumors （P 〈 0.1, P = 0.08）. ADC values of 49 benign nodules and 47 malignant tumors reduced gradually with b value increasing, and differences had statistical significance （F = 7.609, P = 0.001; F = 7.045, P = 0.001）. The ADC values obtained from each b value were profit differentiation between malignant tumors and benign lesions （Az 〉 0.5）. The area under the ROC curve with b value of 800 s/mm^2 was the largest. The ADC in the 48 malignant tumors was [（1.07 ± 0.23） × 10^ - 3 mm^2/s], significantly lower than that of 50 benign lesions [（1.88 ±0.41） × 10^- 3 mm^2/s, P=-0.000] with b value of 800 s/mm^2. Setting ADC ≤ 1.380× 10 ^- 3 mm^2/s as the threshold, the sensitivity and specificity of ADC for differentiating malignant from benign lesions was 97.90% and 88.00% respectively. The accuracy was 93.87%. Conclusion ADC values ean be used as the quantitative standards for differential diagnosis in malignant and benign lesions.