Reduced F-18 fluorodeoxyglucose uptake within marrow after external beam radiation

Purpose: The authors examined the delayed effects of external beam radiatio n on the metabolism of intravertebral marrow cavities. Materials and Methods: Two neurologically normal persons who had completed a full course of external beam radiotherapy for squamous cell carcinoma of the head and neck had positron emission tomography (PET) scans with F-18 fl uorodeoxyglucose (FDG) to identify residual neoplasm. Results: Abnormally low uptake of F-18 FDG was noted within the central mar row cavities of the cervical vertebral bodies in both cases. Conclusions: Diminished metabolic activity within irradiated marrow can be revealed by F-18 FDG PET imaging techniques. Further correlative MRI PET st udies are needed to determine if this postradiation phenomenon is related t o fatty infiltration of the marrow cavity.