Objective: Evaluation of nasopharyngeal carcinoma (NPC) using 18F-FDG PET/CT is limited due to artifact from the intense physiologic uptake of 18F-FDG in the brain.We attempted to improve detection of intracranial tumor invasion (including better delineation of invasion near the skull base) in locally advanced NPC using 11C-choline (11C-CHO) PET/CT.Methods: Fifteen patients with newly diagnosed or recurrent locally advanced NPC were enrolled in the study.18 F-FDG and 11C-choline PET/CT were performed on all patients.PET/CT images obtained using the two tracers were compared using both SUVmax and tumor/brain (T/B)ratios.All patients were followed up for more than one year.Results: The sensitivity of 18F-FDG PET/CT in detecting locally advanced NPC was 86.6% compared to a 100% sensitivity with 11C-CHO PET/CT (t =2.143, P =0.483).The SUVmax of lesions detected using 18F-FDG was higher compared to 11C-CHO (12.81 ±5.00 vs.6.84 ± 2.76, t =6.416, P =0.000), but 11C-CHO had a much higher T/B ratio than 18F-FDG (18.62 ± 7.95 vs.1.38 ± 0.59, t =8.801, P =0.000).Compared with 18F-FDG PET/CT, 11C-CHO PET/CT improved the delineation of intracranial invasion in 50% of patients (x2 =8.00, P =0.014), skull base invasion in 28.5% of patients and orbital invasion in 3/3 patients.Conclusions: 11C-CHO can improve the quality of PET/CT in the T staging of NPC.