[F]Fluorocholine Uptake of Parathyroid Adenoma Is Correlated with Parathyroid Hormone Level.

Purpose: The aim of the study was to investigate the relationship between [F]fluoromethyl-dimethyl-2-hydroxyethylammonium ([F]FCh) positron emission tomography (PET) parameters, laboratory parameters, and postoperative histopathological results in patients with primary hyperparathyroidism (pHPT) due to parathyroid adenomas.

Procedures: This retrospective study was conducted in 52 patients with biochemically proven pHPT. [F]FCh-PET parameters (maximum standardized uptake value: SUV in early phase (after 2 min) and late phase (after 50 min), metabolic volume, and adenoma-to-background ratio (ABR), preoperative laboratory results (PTH and serum calcium concentration), and postoperative histopathology (location, size, volume, and weight of adenoma) were assessed. Relationship of PET parameters, laboratory parameters, and histopathological parameters was assessed using the Mann-Whitney U test and Spearman correlation coefficient. MRI characteristics of parathyroid adenomas were also analyzed.

Results: The majority of patients underwent a PET/MR scan, 42 patients (80.7 %); 10 patients (19.3 %) underwent PET/CT. We found a strong positive correlation between late-phase SUV and preoperative PTH level (r = 0.768, p < 0.001) and between late-phase ABR and preoperative PTH level (r = 0.680, p < 0.001). The surgical specimen volume was positively correlated with the PET/MR lesion volume (r = 0.659, p < 0.001). No significant association was observed between other [F]FCh-PET parameters, laboratory parameters, and histopathological findings. Cystic adenomas were larger than non-cystic adenomas (p = 0.048).

Conclusions: [F]FCh uptake of parathyroid adenomas is strongly correlated with preoperative PTH serum concentration. Therefore, the preoperative PTH level might potentially be able to predict success of [F]FCh-PET imaging in hyperparathyroidism, with higher lesion-to-background ratios being expected in patients with high PTH. PET/MR is accurate in estimating the volume of parathyroid adenomas.