磁共振成像对肺癌淋巴结转移的诊断价值

目的:探讨磁共振成像对肺癌淋巴结转移的诊断价值。材料及方法:将55例肺癌病人术前MRI显示淋巴结的情况与术后比较,以直径在1cm及1.5cm为阈值计算其敏感性、特异性、准确性、阳性预测值及阴性预测值;应用DIASONICS0.35T超导成像系统行T1及T2加权成像。结果:87.3％(48例)的病人MRI可见肺门及纵隔淋巴结肿大,共133个,其中119个信号在T1WI及T2WI上与肿瘤相似,占89.5％;另14个比肿瘤信号略低,占10.5％。手术摘除淋巴结150个,MRI漏计17个,占11.3％。150个淋巴结中44例(80％)74个(49.3％)有转移。1cm以下的淋巴结转移率为5.9％(2/34),1cm～1.5cm的淋巴结转移率为42.3％(30/71),1.5cm以上的转移率为93.3％(42/45)。按1cm及1.5cm以上为阈值,其敏感性、特异性、准确性、阳性预测值及阴性预测值分别为97.3％、52.6％、74.6％、66.7％、95.2％及56.8％、96.1％、76.7％、93.3％、69.5％。结论:MRI显示淋巴结虽有许多优点,但判断淋巴结有无转移仍只能以大小作为标准,信号强度帮助不大;作者认为MRI可采用与CT相似的标准,即将1cm—1.5cm的淋巴结列为可疑,1.5cm以上的定为转移;是否增强以后信号强度对鉴别诊断有所帮助有待于进一步研究。

Evaluation of MRI in the Diagnosis of Metastatic Lymph Nodes of Lung Cancer

Objective: To evaluate the value of MRI in the diagnosis of T 1 and T 2 weighted imagings on 55 patients with lung cancer using a Diasonics 0.35 tesla super - conducting imaging system. The MRI findings of lymph nodes were compared with the operation results. The sensitivity, specificity, accuracy, positive predictive value and negative predictive value were calculated respectively on thresholds of 1 cm and 1.5 cm. Results: 133 lymph nodes in 87.3 % (48 cases) patients were found by MR imaging, with the signal intensities of the 119 nodes appearing similar to the primary masses on both T 1 and T 2 weighted imagings, while those of the other 14 nodes being lower than the primary masses The number of lymph nodes found in the operation were 150 They were divided into three groups(under 1 cm, 1 - 1.5 cm and beyond 1.5 cm)according to their sizes Among them, 74 (from 44 cases) were metastatic ones pathologically; the metastatic rates were 5.9% (2/34), 42.3 % (30/71) and 93.3 % (42/45) respectively for the three groups. The sensitivity, specificity, accuracy, positive predictive value and negative predictive values calculated according to the threshold of 1 cm and 1.5 cm were 97.3 % , 52.6 % , 74.6 % , 66.7 % , 95.2 % and 56.8 % , 96.1 % , 76.7 % , 93.3 % , 69.5 % respectively. Conclusion: Although MRI has some advantages in demonstrating mediastinal lymph nodes, without any advantages in judging the metastatic ones, the criteria is still based on the size of lymph nodes. The signal intensities provide no significance to the diagnosis. The authors considered that the criteria used in CT can also be applied in MRI, i. e. 1 cm- 1.5 cm as suspected and over still in 1.5 cm as definite. MRI enhancement scanning in distinguishing metastatic lymph nodes from benign ones is need still in as definite for further studies.