MEDIASTINAL LYMPH-NODE STAGING OF NON-SMALL-CELL LUNG-CANCER - A PROSPECTIVE COMPARISON OF COMPUTED-TOMOGRAPHY AND POSITRON EMISSION TOMOGRAPHY

We compared the abilities of positron emission tomography and computed tomography to detect N2 or N3 lymph node metastases (N2 or N3) in pat ients with lung cancer, Positron emission tomography detects increased rates of glucose uptake, characteristic of malignant cells, Patients with peripheral tumors smaller than 2 cm and a normal mediastinum were ineligible, All patients underwent computed tomography, positron emis sion tomography, and surgical staging, The American Thoracic Society l ymph node map was used, Computed and positron emission tomographic sca ns were read by separate radiologists blinded to surgical staging resu lts, Lymph nodes were ''positive'' by computed tomography if larger th an 1.0 cm in short-axis diameter, Standardized uptake values were reco rded from areas on positron emission tomography corresponding to those from which biopsy specimens were taken; if greater than 4.2, they wer e called ''positive.'' Seventy-five lymph node stations (2.8 per patie nt) were analyzed in 27 patients, Computed tomography incorrectly stag ed the mediastinum as positive for metastases in three patients and as negative for metastases in three patients, Sensitivity and specificit y of computed tomographic scans were 67% and 83%, respectively, Positr on emission tomography correctly staged the mediastinum in all 27 pati ents, When analyzed by individual node station, there were four false positive and four false negative results by computed tomography (sensi tivity = 60%, specificity = 93%, positive predictive value = 60%). Pos itron emission tomography mislabeled one node station as positive (100 % sensitive, 98% specific, positive predictive value 91%. The differen ces were significant when the data were analyzed both for individual l ymph node stations (p = 0.039) and for patients (p = 0.031) (McNemar t est), Positron emission tomography and computed tomography are more ac curate than computed tomography alone in detecting mediastinal lymph n ode metastases from non-small-cell lung cancer.