How to Select the Optimal Diagnostic Criteria for Detection of Mediastinal Lymph Node Metastasis by Computed Tomography?

The most appropriate criterion level for detecting lung cancer lymph node metastasis was studied by CT. The subjects consisted of 156 operated cases of lung cancer, 73 squamous cell carcinoma cases, 67 adenocarcinoma, 16 miscellaneous. The longest dimension, shortest dimension, longest dimension plus shortest dimension, and longest dimension times shortest dimension of the mediastinal lymph nodes were used as indicators of the diagnosis. From the result of ROC curve analysis, the longest dimension plus shortest dimension of the lymph nodes showed the highest accuracy of diagnosis of metastasis. Metastasis of squamous cell carcinoma was diagnosed more accurately than that of adenocarcinoma. For squamous cell carcinoma, a longest dimension plus a shortest dimension of 19 mm and a longest dimension times shortest dimension of 90 mm2 revealed almost the same result with a sensitivity of 79.4%, 79.1% and specificity of 85.0%, 85.0%, respectively. For adenocarcinoma, 14 mm of longest dimension plus shortest dimension was optimal, with sensitivity of 74.7%, specificity of 79.9%. Not only the histologic types, but mediastinal regions might be thought to influence the criteria level. It appears best to use the smaller criteria level for upper mediastinal lymph nodes than lower mediastinal nodes. It was suggested that criteria level of lymph node metastasis was influenced by the histologic type and the region.