¹⁸F-NaF-PET/CT in patients with primary hyperparathyroidism and brown tumors

Introduction: Brown tumors (BT) are non-neoplastic bone lesions infrequently occurring in patients with long-standing severe hyperparathyroidism (HPT). BT may be identified and characterized using 18-F-sodium fluoride-positron-emission-tomography/computed tomography (¹⁸F-NaF-PET/CT). We present a retrospective series of eight primary hyperparathyroidism (pHPT) patients with BT imaged with ¹⁸F-NaF-PET/CT.

Materials and methods: Imaging assessment included location, diameter, maximum standardized uptake value (SUV_max), metabolically active lesion volume (PET_vol) of BT, total metabolically active bone volume (TMB_vol) per patient and several computed tomography (CT) features of BT. Where appropriate, we analyzed the association between characteristic features of BT in ¹⁸F-NaF-PET/CT, histopathology, clinical symptomatology and laboratory parameters.

Results: In our cohort of 8 patients (median age, 49 years, range, 26-73), 72 BT were found. The mean PET_vol of BT was 89.48 cm³ ± 122.81 cm³ and the mean SUV_max was 17.5 ± 7.8. The total PET_vol of BT per patient correlated positively with serum calcium (r = 0.810, p = 0.015), and negatively with glomerular filtration rate (GFR) (r = - 0.762, p = 0.028). TMB_vol correlated significantly with serum PTH (r = 0.810, p = 0.015), alkaline phosphatase (r = 0.762, p = 0.028), and duration of postoperative hospitalization (r = 0.826, p = 0.011, 24.3 days ± 19.8 days).

Conclusion: ¹⁸F-NaF-PET/CT is a valuable non-invasive whole-body imaging technique for the assessment of patients with pHPT and BT. TMB_vol is associated with PTH and alkaline phosphatase, and the requirement for intense postoperative calcium substitution, which determines the duration of hospitalization.