Change induced by radiation therapy in FDG uptake in normal and malignant structures of the head and neck: Quantitation with PET

PURPOSE: To quantitate the changes induced in uptake of the glucose analog 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) in normal structures in the head and neck and compare these to the change in uptake in malignant structures in patients with head and neck tumors undergoing radiation therapy. MATERIALS AND METHODS: Eleven patients with biopsy-confirmed squamous cell carcinoma of the head and neck were studied before, during, and after a 6-week course of radiation therapy with positron emission tomography (PET)-FDG imaging. A ratio of FDG uptake in the structure compared with that in the cerebellum (termed metabolic ratio) within and outside of the field of radiation was determined in the adenoids; lingual and palatine tonsils; parotid, submandibular, and sublingual glands; and nasal turbinates, soft palate, and gingiva. RESULTS: The average metabolic ratio in the tonsils, nasal turbinates, soft palate, and gingiva did not change significantly with treatment. CONCLUSION: FDG uptake in normal structures does not change with radiation therapy. This fact is in marked contrast to the FDG uptake in squamous cell carcinomas in the head and neck, which decrease dramatically with treatment (P < .005).