Abstract
BACKGROUND: Patients with differentiated thyroid cancer (DTC) are referred to radioactive (131)I (RAI) therapy and post-therapy (131)I whole-body scintigraphy (WBS) to identify local and/or remote metastases. Positron emission tomography (PET)/computed tomography (CT) imaging with (18)F-fluoro-D-glucose (FDG) or (18)F-sodium fluoride (NaF) may also be used with these patients for the evaluation of bone metastases. We compared the role of (18)F-NaF PET/CT and (18)F-FDG-PET/CT in patients with DTC and documented bone metastases at post-therapy WBS. METHODS: Ten consecutive DTC patients with iodine avid bone metastasis at post-therapy WBS referred to (18)F-NaF PET/CT and (18)F-FDG PET/CT were studied. The findings of the three imaging procedures were compared for abnormal detection rates and concordance. RESULTS: At post-therapy (131)I WBS, all patients had skeletal involvement with a total of 21 bone iodine avid lesions. At (18)F-FDG PET/TC, 19 bone lesions demonstrated increased tracer uptake and CT pathological alterations, while 2 lesions did not show any pathological finding. At (18)F-NaF PET/CT, the 19 bone lesions detected at (18)F-FDG PET/TC also demonstrated abnormal tracer uptake, and the other 2 bone iodine avid foci did not show any pathological finding. CONCLUSIONS: In patients with DTC, (18)F-NaF PET/CT did not obtain more information on the metastatic skeletal involvement than post-therapy (131)I WBS and (18)F-FDG PET/CT.