Tumor Burden of Iodine-Avid Bone Metastatic Thyroid Cancer Identified via ¹⁸F-Sodium Fluoride PET/CT Imaging

Patients with differentiated thyroid cancer (DTC) are referred to radioactive ¹³¹I (RAI) therapy and post-therapy ¹³¹I whole-body scintigraphy (WBS) to identify local and/or remote metastases. Positron emission tomography (PET)/computed tomography (CT) imaging with ¹⁸F-fluoro-D-glucose (FDG) or ¹⁸F-sodium fluoride (NaF) may also be used with these patients for the evaluation of bone metastases. We compared the role of ¹⁸F-NaF PET/CT and ¹⁸F-FDG-PET/CT in patients with DTC and documented bone metastases at post-therapy WBS.

Ten consecutive DTC patients with iodine avid bone metastasis at post-therapy WBS referred to ¹⁸F-NaF PET/CT and ¹⁸F-FDG PET/CT were studied. The findings of the three imaging procedures were compared for abnormal detection rates and concordance.

At post-therapy ¹³¹I WBS, all patients had skeletal involvement with a total of 21 bone iodine avid lesions. At ¹⁸F-FDG PET/TC, 19 bone lesions demonstrated increased tracer uptake and CT pathological alterations, while 2 lesions did not show any pathological finding. At ¹⁸F-NaF PET/CT, the 19 bone lesions detected at ¹⁸F-FDG PET/TC also demonstrated abnormal tracer uptake, and the other 2 bone iodine avid foci did not show any pathological finding.

In patients with DTC, ¹⁸F-NaF PET/CT did not obtain more information on the metastatic skeletal involvement than post-therapy ¹³¹I WBS and ¹⁸F-FDG PET/CT.