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Preliminary Study of 11C-Choline PET/CT for T Staging of Locally Advanced Nasopharyngeal Carcinoma: Comparison with 18F-FDG PET/CT

Evaluation of nasopharyngeal carcinoma (NPC) using 18F-FDG PET/CT is limited by 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 using11C-choline PET/CT. Methods: Fifteen patients with newly diagnosed or recurrent locally advanced NPC were enrolled in the study. 18F-FDG and 11C-choline PET/CT was performed on all patients. PET/CT images obtained using the 2 tracers were compared using both maximum standardized uptake value (SUVmax) and tumor-to-brain (T/B) ratios. All patients were followed up for more than 1 y. Results: The sensitivity of 18F-FDG PET/CT in detecting locally advanced NPC was 86.6%, compared with a 100% sensitivity for 11C-choline PET/CT (t = 2.143, P = 0.483). The SUVmax of lesions detected was higher using 18F-FDG than using 11C-choline (12.81 ± 5.00 vs. 6.84 ± 2.76, t = 6.416, P < 0.001), but the T/B ratio was much higher for 11C-choline than for 18F-FDG (18.62 ± 7.95 vs. 1.38 ± 0.59, t = 8.801, P < 0.001). Compared with 18F-FDG PET/CT, 11C-choline PET/CT improved the delineation of intracranial invasion in 6 of 12 patients (χ2 = 8.00, P = 0.014), skull base invasion in 4 of 14 patients, and orbital invasion in 3 of 3 patients. Conclusion: 11C-choline can improve the quality of PET/CT in the T staging of NPC.