Comparison of Preoperative Thoracic CT Scan of Hilar and Mediastinal Lymph Nodes and Pathologic Diagnosis in Non-small-cell Lung Cancer

Objective To compare the results among preoperative thoracic CT of hilar and mediastinal lymph nodes,surgical finding and postoperative lymph node metastasis confirmed by pathology in the patients with non-small-cell lung cancer (NSCLC) in order to evaluate the accuracy of CT in the assessment of hilar and mediastinal node metastasis.Methods From June 2001 to May 2003,86 patients with NSCLC were retrospectively studied.All the patients had preoperative thoracic CT,surgical finding and postoperative pathologic results in lymph node metastasis.Hilar and mediastinal lymph nodes were considered abnormal if they exceeded 10 mm in the short axis diameter.Result The sensibility and specificity of CT for hilar and mediastinal lymph nodes metastasis had cosely relation with the diameter(s) of lymph nodes.The metastasis rate was 16%(12/27) when the short diameter of lymph nodes were under 10 mm,while 40%(54/136) in 10-19 mm,75%(27/36)in 20-29 mm and 6/6 beyond 30 mm.The overall sensitivity rate of CT for hilar and mediastinal nodes was 66% and specificity 51%.Conclusions CT has rather high evaluation on the diagnosis of hilar and mediastinal nodes in NSCLC,and metastasis rate is high especially when the lymph nodes beyond 20 mm.The factors influencing the accuracy of CT include the lymph node size and the presence of tumor-induced obstructive pneumonitis and atelectasis.The other factors including the locations of primary tumor and lymph nodes,long history of smoking and chronic bronchitis do not influence the accuracy of CT in the evaluation of thoracic lymph nodes.