Evaluation of Bone Invasion in Gingival Squamous Cell Carcinoma Using PET/CT Radiomics

Background: Accurate preoperative assessment of bone invasion is essential for surgical planning in gingival squamous cell carcinoma (SCC). This study evaluated the diagnostic value of conventional ¹⁸F-FDG PET/CT-derived imaging parameters and PET-based radiomic features for predicting histopathologic bone invasion. Methods: This retrospective study included 68 patients with gingival SCC who underwent preoperative ¹⁸F-FDG PET/CT followed by primary surgical treatment. Bone invasion was confirmed histopathologically. Conventional PET parameters (MTD, SUVmax, SUVmean, MTV, and TLG) and PET-based radiomic features were extracted from the primary tumor. Group comparisons, receiver operating characteristic (ROC) analysis, and univariate logistic regression were performed. Results: Patients with bone invasion showed significantly higher MTD, SUVmax, MTV, and TLG than those without bone invasion (all p < 0.05), whereas SUVmean was not significantly different. Entropy, correlation, and zone entropy were significantly higher in the bone invasion-positive group. MTV showed the numerically highest AUC among conventional PET parameters (AUC = 0.748), whereas correlation (AUC = 0.725) and zone entropy (AUC = 0.714) showed the highest performance among radiomic features. Univariate logistic regression showed significant associations of MTD, MTV, TLG, entropy, correlation, and zone entropy with bone invasion. Conclusions: Conventional PET parameters and PET-based radiomic features were significantly associated with histopathologic bone invasion in gingival SCC. Radiomic features reflecting intratumoral heterogeneity may complement conventional metabolic parameters and improve preoperative assessment of bone invasion.