Delayed total-body [18F]FDG PET/CT demonstrates systemic vascular inflammation after concurrent chemoradiotherapy in patients with head and neck cancer.

PURPOSE: To investigate the feasibility of 2-h-delayed total-body [18F]FDG PET/CT for detecting vascular inflammation after concurrent chemoradiotherapy (CCRT) in head-and-neck-cancer (HNC) patients and to exploratorily assess its association with cardiovascular-related events (CVRE). METHODS: Twenty-four HNC patients underwent 2-h total-body [18F]FDG PET/CT before and 3 months after CCRT and were followed for CVRE. Vascular inflammation was evaluated across eleven arterial segments. Slice-based mean standardized uptake values (SUVmean) were normalized to the superior vena cava (SVC) to derive the target-to-background ratio (TBRmean), and segmental averages (avgTBRmean) were calculated. Pre- and post-CCRT avgTBRmean were compared, and the relative difference (RD-avgTBRmean) was analyzed for association with radiation dose and CVRE. RESULTS: Post-CCRT PET demonstrated increased avgTBRmean in all arterial segments, with significant increases in the carotid arteries (left: 1.32 vs 1.20, P < 0.001; right: 1.34 vs 1.24, P = 0.018), subclavian arteries (left: 1.20 vs 1.14, P = 0.022; right: 1.18 vs 1.10, P = 0.019), and infrarenal abdominal aorta (1.08 vs 0.96, P < 0.001). Mean radiotherapy dose correlated with both post-CCRT avgTBRmean (r = 0.289, P = 0.002) and RD-avgTBRmean (r = 0.251, P = 0.008). Patient-based average RD-avgTBRmean was higher in patients with CVRE (12.1% ± 6.7% vs. 4.5% ± 6.5%, P = 0.032). However, no independent association remained after age adjustment. The SUVmean of SVC was comparable between pre- and post-CCRT PET. CONCLUSION: Delayed total-body [18F]FDG PET/CT demonstrated CCRT-related vascular inflammation in HNC patients, suggesting a potential imaging biomarker of treatment-related cardiovascular risk but warrants validation in larger studies.