POSITRON EMISSION TOMOGRAPHY OF LUNG-TUMORS AND MEDIASTINAL LYMPH-NODES USING [F-18] FLUORODEOXYGLUCOSE

Positron emission tomography detects increased glucose uptake in malig nant tissue using the glucose analogue [2-F-18]fluoro-2-deoxy-D-glucos e. We reviewed the scans obtained in 62 patients with lung tumors. All had undergone computed tomography and had tissue-based diagnoses: 22 had adenocarcinomas, 12 had squamous cell carcinomas, 13 had other mal ignancies, 1 had organizing pneumonia, 1 had a hamartoma, and 13 had g ranulomas. Positron emission tomography with [2-F-18]fluoro-2-deoxy-D- glucose identified 44 of 47 malignancies. Two of three false-negative findings were tumors that were 1 cm(2) or less and the other was a bro nchioloalveolar carcinoma. All three false-positive findings were gran ulomas. The sensitivity and specificity of the technique were 93.6% an d 80%, respectively, and the positive and negative predictive values w ere 93.6% and 80%, respectively. The differential uptake ratio was det ermined in all 62 patients. The mean differential uptake ratio (+/- th e standard error of the mean) for malignant tumors was 6.4 +/- 0.56 an d that for benign tumors was 1.14 +/- 0.26 (p < 0.0001, t test). Twent y-five of the patients had N2 lymph nodes evaluated pathologically. Po sitron emission tomography with [2-F-18]fluoro-2-deoxy-D-glucose ident ified negative N2 nodes in 19 of 22 patients (86%) with negative nodes and positive N2 nodes in 2 of 3 patients (66%) with positive nodes, i ncluding one instance missed by computed tomography. Positron emission tomography with [2-F-18]fluoro-2-deoxy-D-glucose is a highly accurate and noninvasive method for identifying malignant lung tumors. The cli nical application of this imaging technique in the evaluation of N2 ly mph nodes awaits the results of ongoing prospective studies.