Overestimated value of 18F- FDG PET/ CT to diagnose pulmonary nodules: Analysis of 298 patients

AIM: To investigate the accuracy and efficacy of combined 2-[F-18]- fluoro-2-deoxy-d-glucose (FDG) positron-emission tomography (PET)/computed tomography (CT) in the diagnosis of pulmonary nodules. MATERIAL AND METHODS: The present retrospective study included 298 patients with clinically suspected pulmonary malignancy who underwent preoperative PET/CT. The results of PET/CT were compared with the histopathological findings after thoracotomy or thoracoscopic surgery. RESULTS: Of 298 patients, pulmonary malignancy was histopathologically diagnosed in 248 and benign lesions in 50 patients. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of PET/CT in detecting malignant lesions were 80.2%, 38%, 86.5%, 27.9%, and 73.1%, respectively. The specificity and NPV were very low, and the area under curve (AUC) in the receiver operating characteristic (ROC) curve analysis was 0.694. For 219 patients with non- small cell lung cancer (NSCLC), falsely negative results occurred in 43 patients. The multivariate risk- factor analysis identified high differentiation ( p < 0.001), peripheral lung cancer (p = 0.016), non- pleural invasion (p = 0.001), tumour size <= 3 cm (p = 0.026), adenocarcinoma (p = 0.062) and non- smoker (p = 0.066) as risk factors for false negatives.. CONCLUSION: The study suggests that the role of PET/CT in the detection of pulmonary malignancy has been overestimated in the past. It warrants attention that high differentiation, peripheral lung cancer, non- pleural invasion, tumour size = 3 cm, adenocarcinoma, and nonsmoker were independent risk factors for negative PET/CT findings of NSCLC.. (C) 2014 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.