Comparison of F-NaF PET/CT with Other Imaging Methods in the Detection of Bone Metastases in Patients with Medullary Thyroid Cancer: a Report of a Series of 31 Cases.

Purpose: To compare the F-NaF PET/CT studies (F-NaF) with other imaging methods in the detection of skeletal metastases (SM) in patients with medullary thyroid cancer (MTC).

Methods: We retrospectively analyzed 31 patients with MTC who performed F-NaF to assess SM. The results of the F-NaF were compared with other imaging methods performed for metastasis detection: Tc-MDP bone scan (BS), magnetic resonance imaging (MRI), contrast-enhanced CT (CT), and Ga-Dotatate and F-FDG PET/CT studies. A qualitative analysis comparing the F-NaF findings with the ones of the other methods was performed, and the results were classified as superior (>), equal (=), and inferior (<).

Results: Eleven patients had no bone metastases detected on any of the imaging methods used. Twenty patients presented SM depicted on F-NaF. Of these 20 patients, 12 performed bone scan (in 9 F-NaF > BS and in 3 F-NaF = BS), 1 performed F-FDG (F-NaF > F-FDG), 4 performed Ga-Dotatate (in 2 F-NaF > Ga-Dotatate and in 2 F-NaF = Ga-Dotatate), 20 performed CT of at least one body segment (in 15 F-NaF = CT and in 5 F-NaF > CT), and 16 performed MRI of at least one body segment, and in all of them, the F-NaF was equal to the MRI. Beside this, the F-NaF detected SM in body segments not routinely scanned in MRI and CT.

Conclusion: In patients with MTC, the F-NaF seems to be equal or superior to other imaging modalities in the detection of SM and allows the analysis of the whole skeletal in a single study.