3．0T磁共振扩散加权成像对肺部良恶性肿块的诊断价值

目的探讨3．0T磁共振扩散加权成像（DWI）对肺部良、恶性肿块的诊断价值。方法56例经CT扫描和手术证实的周围型肺部肿块行MRI常规和DWI扫描（b=0、300、500、700、900s·mm^-2），并得到各b值的表观扩散系数（ADC）值，采用5分制评分法对2种参照物（胸髓和胸壁肌肉）DWI的病灶信号强度进行评分，采用t检验和ROC曲线进行对比并评价DWI诊断肺部良恶性病灶的敏感性、特异性，同时对各b值对应的ADC值进行量化分析。结果以肌肉为参照时，肺癌和良性病变的DWI信号强度评分分别为（3．97±1．21）、（2．55±1．46）分，两者比较差异有统计学意义（P=0．00036）；病灶的信号强度≥3判为癌症，其诊断敏感性为86．8％，特异性为66．7％。以胸髓为参照时，肺癌和良性病变的DWI信号强度评分分别为（4．23±0．99）、（2．94±1．43）分，两者比较差异有统计学意义（P=0．00025）；病灶的信号强度≥3判为癌症，其诊断敏感性为94．7％和特异性为50．0％。以肌肉和胸髓为参照的ROC曲线下面积分别为0．768、0．729，两者比较差异无统计学意义（P〉0．05）。从2种评分方式的诊断能力来看，以肌肉为参照的评分方式略优于以胸髓为参照。各b值不同病理类型肺癌与肺部炎症ADC值差异均无统计学意义。结论3．0T磁共振行肺部DWI成像，DWI的信号强度有助于良恶性病变的鉴别诊断，以肌肉为参照具有较高的敏感性和特异性，肺部ADC值不能作为定量诊断标准。DWI可能成为肺部良恶性肿块鉴别诊断的一种新的辅助技术手段。

Diagnostic Value of 3.0T Magnetic Resonance Diffusion-weighted Imaging in Benign and Malignant Lung Tumors

Objective To evaluate the value of 3.0T magnetic resonance diffusion-weighted imaging （DWI） in differentiating the malignant from benign pulmonary masses. Methods Fifty-six patients with CT and reseetion proved peripheral lung tumors underwent MRI and DWI（b value： 0,300,500,700 and 900 s · mm ^-2）,and different ADCs were generated. Signal intensity on DWI images was scored by 5-point method with comparison to thoracic and chest wall muscles,and the sensitivity and specifieity of DWI were used to evaluate the characteristics of masses by analyzing t test and ROC curve. The quantitative ADC was obtained corresponding to the specific regions of interest with different b values. Results The mean score of malignant pulmonary tumors （3.97±1.21）was significantly higher than that of benign nodules （2.55±1.46）when thoracic muscle was used as reference（P =0. 000 36）. Lesions with intensity greater than or equal to the reference were judged as lung cancer,and the diagnostic sensitivity and specificity were 86.8% and 66.7%, respectively. The mean score of malignant pulmonary tumors （4.23±0.99）was significantly higher than that of benign nodules （2.94±1.43）when spinal cord was used as reference（P=0. 000 25）. Lesions with intensity greater than or equal to the reference were judged as lung cancer,and the diagnostic sensitivity and specificity were 94.7 % and 50.0 %, respectively. The diagnostic ability of chest wall muscle as reference with the area under ROC curve （0. 768） was a little better than that of spinal cord as reference with the area under ROC curve （0. 729）（P〉0.05）. There was no statistical significance between lung cancer and inflammation of varying b values in ADC maps. Conclusion Signal intensity on 3.0T magnetic resonance DWI images is helpful for the differential diagnosis between the benign and malignant lung lesions. The chest wall muscle as a reference has high diagnostic sensitivity and specificity. ADC values can not be used as the quantitative standards for differential diagnosis in lung diseases. DWI may be a potential assistive technology for differential diagnosis of pulmonary neoplasms.