Comparison of 18 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 18 F-NaF PET/CT studies (18 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 18 F-NaF to assess SM. The results of the 18 F-NaF were compared with other imaging methods performed for metastasis detection: 99 Tc-MDP bone scan (BS), magnetic resonance imaging (MRI), contrast-enhanced CT (CT), and 68 Ga-Dotatate and 18 F-FDG PET/CT studies. A qualitative analysis comparing the 18 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 18 F-NaF. Of these 20 patients, 12 performed bone scan (in 9 18 F-NaF > BS and in 3 18 F-NaF = BS), 1 performed 18 F-FDG (18 F-NaF > 18 F-FDG), 4 performed 68 Ga-Dotatate (in 2 18 F-NaF > 68 Ga-Dotatate and in 2 18 F-NaF = 68 Ga-Dotatate), 20 performed CT of at least one body segment (in 15 18 F-NaF = CT and in 5 18 F-NaF > CT), and 16 performed MRI of at least one body segment, and in all of them, the 18 F-NaF was equal to the MRI. Beside this, the 18 F-NaF detected SM in body segments not routinely scanned in MRI and CT.

Conclusion: In patients with MTC, the 18 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.