STAGING OF THE MEDIASTINUM - VALUE OF POSITRON EMISSION TOMOGRAPHY IMAGING IN NONSMALL CELL LUNG-CANCER

Recent studies have shown limitations of morphological imaging in stag ing mediastinal lymph node involvement in lung cancer, In contrast to computed tomography (CT), which depends primarily on anatomical imagin g features, positron emission tomography (PET) with 18-fluorodeoxygluc ose (FDG) depends mainly on the metabolic characteristics of a tissue for the diagnosis of disease. We have performed a prospective study co mparing FDG-PET and CT of the thorax in the presurgical assessment of the mediastinum in 50 patients with newly diagnosed non-small cell lun g cancer (NSCLC). CT and PET scans were interpreted separately, and re sults were compared to pathological staging obtained during thoracotom y. Hilar or mediastinal lymph node involvement was present in 58%, In staging for lymph node involvement, CT had a sensitivity of 72% and sp ecificity of 81%, whereas PET had a sensitivity and specificity of 90% and 86%, respectively. When the PET study was compared to histologica l results, there were four cases showing more advanced mediastinal inv olvement with PET and four cases showing less involvement with PET. Fr om our preliminary results, we conclude that positron emission tomogra phy with 18-fluorodeoxyglucose is significantly more accurate than com puted tomography in the mediastinal staging of non-small cell lung can cer.