18F-NaF uptake in skull-base bone as a predictor of treatment response in advanced nasopharyngeal carcinoma

This study investigates the utility of ¹⁸F-sodium fluoride (¹⁸F-NaF) positron emission tomography/computed tomography (PET/CT) in assessing skull-base bone invasion (SBBI) and predicting treatment response in advanced nasopharyngeal carcinoma (NPC). A retrospective analysis was conducted on 142 patients with newly diagnosed advanced NPC who underwent ¹⁸F-NaF PET/CT for initial staging from December 2020 to December 2023. ¹⁸F-NaF PET/CT scans were analyzed for uptake values at the skull-base bone, and these were correlated with treatment outcomes of primary tumor using the Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. Statistical analyses involved Mann-Whitney U tests for group comparisons and logistic regression for evaluating risk factors. Higher ¹⁸F-NaF uptake at the skull-base bone was significantly associated with advanced T stages (p < 0.0001) and the presence of bone metastases (p = 0.01). Patients exhibiting complete response (CR) to treatment had significantly lower skull-base ¹⁸F-NaF uptake compared to those with non-CR (p < 0.001). Receiver operating characteristic (ROC) analysis identified an SUV_max > 10.0 and SUV_mean > 5.2 as predictive of non-CR, with AUC values of 0.77 and 0.76, respectively. Univariate and multivariable analysis confirmed SUV_max as a significant predictor of treatment response (OR = 7.03, 95% CI: 1.97-25.13, p < 0.05). Elevated ¹⁸F-NaF uptake at the skull-base bone is predictive of poorer treatment outcomes, highlighting its potential as a prognostic biomarker in advanced NPC. This study demonstrates that ¹⁸F-NaF PET/CT is a valuable imaging modality for evaluating SBBI in NPC, offering metabolic information that complements the anatomical findings from MRI.