F-18 FDG PET/CT Characteristics of a Lung Lesion and Concomitant Findings as Histopathology Predictors: A Single-Center Experience

Objectives: The study aims to investigate the predictive potential of fluorine-18 fluorodeoxyglucose (F-18 FDG) positron-emission tomography/ computed tomography (PET/CT) characteristics of a lung lesion of an unknown etiology and concomitant findings in a diagnosis of a malignancy, as well as to evaluate a difference in glucose metabolism between different types of lung cancer. Material and Methods: The retrospective study enrolled patients who underwent F-18 FDG PET/CT for the evaluation of a lung lesion of an unknown etiology. All of the included patients went through biopsy with a histopathological confirmation of the etiology aft er the examination. Results: The size of a lesion, progression on previous CT examinations, higher maximum standardized uptake value (SUVmax), with the sensitivity of 83.1% and the specificity of 82.6% for the SUVmax cutoff value of 3.8 (area under the curve 0.874; 95% confidence interval [CI], 0.788–0.961; receiver operating characteristic curve analysis for the quantitative test), increasing age, and smoking were the statistically significant predictors of malignant etiology, with lesions larger than 20 mm being 4.8 times more likely to be malignant than smaller ones. The presence of extrapulmonary focal zones of an increased glucose metabolism was an indicator of a malignant etiology (odds ratio [OR] 4.33; 95% CI, 1.33–14.14; P = 0.015, logistic regression analysis), with hypermetabolic mediastinal and hilar lymph nodes being especially good predictors (OR 7.00; 95% CI, 1.51–32.40; P = 0.013, logistic regression analysis). No difference in glucose metabolism quantified by SUVmax between adenocarcinoma, squamous cell carcinoma, and other types of lung cancer was observed. Conclusion: Increasing age, size of a lesion and SUVmax, progression of at least 4 mm on CT, hypermetabolic mediastinal and hilar lymph nodes, and smoking are the predictors of malignancy.