Evaluation of Cavitary Lung Lesions with ¹⁸F-FDG PET/CT: Differentiating Benign from Malignant Lesions

This study aimed to analyze ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT) features to differentiate benign from malignant pulmonary cavitary lesions.

A total of 76 patients with cavitary lung lesions who underwent ¹⁸F-FDG PET/CT imaging were retrospectively analyzed. Patient demographics, histopathological findings, cavitary lesion morphology, CT characteristics, and maximum standard uptake value (SUV_max) of lesions were recorded. Cavitary lesions were classified as benign or malignant and further subdivided by maximum wall thickness into two groups: ≤15 mm and >15 mm. Histopathological results, clinical follow-up, or both were used as the reference standard for lesion classification.

Among 76 patients (mean age, 63.4 years), 31 (40.8%) had benign disease and 45 (59.2%) had malignant disease. Malignant lesions were observed at older ages and exhibited significantly greater lesion size, wall thickness, and SUV_max than those in benign lesions (p<0.05 for all). There were no significant differences between the malignant and benign groups regarding sex, lesion localization, air-fluid levels, or pleural effusion (p>0.05 for all). Peripheral consolidation, multiple cavitary lesions, and tree-in-bud pattern were significantly more prevalent in benign lesions than in malignant lesions (p<0.05 for all). In lesions with a maximum wall thickness ≤15 mm, SUV_max was significantly higher in malignant lesions than in benign lesions (mean values, 9.81 vs. 5.28; p<0.05). Malignant lesions with a maximum wall thickness >15 mm demonstrated higher SUV_max values (mean 18.37 vs. 10.45; p<0.05). SUV_max was independently associated with malignancy (odds ratio: 1.237, p=0.017) and showed the best diagnostic performance (area under the curve=0.866; cut-off 8.58, sensitivity 80%, specificity 77%).

The morphological characteristics of pulmonary cavitary lesions, associated parenchymal findings, and ¹⁸F-FDG uptake patterns on PET/CT provide valuable information for distinguishing between benign and malignant lesions. In this study, SUV_max demonstrated the highest diagnostic performance. The combined evaluation of metabolic and morphological parameters can enhance diagnostic accuracy and support the clinical decision-making process, thereby contributing to the optimal management of patients.