EVALUATION OF THE SOLITARY PULMONARY NODULE BY POSITRON EMISSION TOMOGRAPHY IMAGING

Current noninvasive imaging methods are not sufficiently reliable for accurate detection of malignancy in most solitary pulmonary nodules (S PNs). Positron emission tomography (PET) using 18-fluorodeoxyglucose ( FDG), showing increased FDG uptake and retention in malignant cells, h as proved useful to differentiate malignant from benign tissue and cou ld, therefore, contribute to the evaluation of the SPN. We performed a prospective study of 50 patients referred to the Pneumology Departmen t with unclear diagnoses of SPN after conventional radiological screen ing, PET study was performed on each subject before an invasive proced ure was proposed. Thirty three patients had a malignant nodule and 17 had a benign nodule, The mean size of malignant nodule was 3 cm (range 1.5-4.5 cm). All showed a marked increase in 18-FDG uptake, The mean size of benign nodule was 1.8 cm (range 0.5-3.5 cm), PET imaging showe d the absence of 18-FDG uptake and correctly identified 15 of 17 benig n nodules, There were two false-positive cases with a moderate increas e in 18-FDG uptake (1 postprimary tuberculosis; and 1 anthracosilicoti c nodule with nonspecific inflammation), At present, the sensitivity a nd specificity of the method are 100 and 88%, respectively, The positi ve and negative predictive values of PET imaging for SPNs are 94 and 1 00%, respectively. Our preliminary results demonstrate that PET-FDG im aging is a noninvasive technique, which appears highly accurate in dif ferentiating malignant SPN from benign SPN. (C) ERS Journals Ltd 1996.