Reliability of positron emission tomography–computed tomography in identification of mediastinal lymph node status in patients with non–small cell lung cancer

ObjectiveThe involvement of mediastinal lymph nodes is a very important prognostic factor in patients with potentially resectable non–small cell lung cancer. Our aim in this study was to investigate the value of positron emission tomographic–computed tomographic scanning in staging lung cancer, especially for mediastinal lymph node evaluation, and to determine whether this could decrease the need for mediastinoscopy.MethodsSeventy-eight patients with non–small cell lung cancer who were potential candidates for surgical resection and admitted to the thoracic surgery unit of our hospital from March 2006 to June 2008 joined this prospective study. Positron emission tomographic–computed tomographic scanning was performed as part of the prospective studies used to diagnose or stage the tumors. All 78 patients underwent tissue sampling of mediastinal lymph nodes to compare these with imaging results. The diagnostic efficacy of the computed tomographic and positron emission tomographic–computed tomographic scans compared with histopathologic findings were calculated with sensitivity, specificity, positive and negative predictive values, and accuracy.ResultsFinal histology was available on 397 lymph node stations (N1, N2, and N3) sampled from 78 patients during mediastinoscopy or surgical intervention. Sensitivity, specificity, and positive and negative predictive values of mediastinal lymph node involvement in patients undergoing thoracic computed tomographic scanning were 45.4%, 80.5%, 27.7%, and 90%, respectively. The accuracy of computed tomographic scanning was 75.6%. The sensitivity, specificity, and positive and negative predictive values of mediastinal lymph node involvement in patients undergoing positron emission tomographic–computed tomographic scanning were 81.8%, 89.5%, 56.2%, and 96.7%, respectively.ConclusionThere is a need for mediastinoscopy in positron emission tomographic–computed tomographic scanning–positive mediastinal lymph nodes, but it might not be necessary for positron emission tomographic–computed tomographic scanning–negative lymph nodes