Staging of the mediastinum: value of positron emission tomography imaging in non-small cell lung cancer.

Recent studies have shown limitations of morphological imaging in staging mediastinal lymph node involvement in lung cancer. In contrast to computed tomography (CT), which depends primarily on anatomical imaging features, positron emission tomography (PET) with 18-fluorodeoxyglucose (FDG) depends mainly on the metabolic characteristics of a tissue for the diagnosis of disease. We have performed a prospective study comparing FDG-PET and CT of the thorax in the presurgical assessment of the mediastinum in 50 patients with newly diagnosed non-small cell lung cancer (NSCLC). CT and PET scans were interpreted separately, and results were compared to pathological staging obtained during thoracotomy. Hilar or mediastinal lymph node involvement was present in 58%. In staging for lymph node involvement, CT had a sensitivity of 72% and specificity of 81%, whereas PET had a sensitivity and specificity of 90% and 86%, respectively. When the PET study was compared to histological results, there were four cases showing more advanced mediastinal involvement with PET and four cases showing less involvement with PET. From our preliminary results, we conclude that positron emission tomography with 18-fluorodeoxyglucose is significantly more accurate than computed tomography in the mediastinal staging of non-small cell lung cancer.