Assessment of the role of early dynamic PET/CT with 18F-fluorocholine in detection of parathyroid lesions in patients with primary hyperparathyroidism.

Objective: The aim of the present study was to assess the utility of early dynamic PET/computed tomography with fluorine-18-fluorocholine (F-FCH) in detecting parathyroid lesions and in differentiating parathyroid lesions from cervical lymph nodes (LNs).

Patients And Methods: A prospective study was conducted on 14 patients with clinical and biochemical evidence of primary hyperparathyroidism by having a positive Tc-sestaMIBI scan. Patients underwent early dynamic F-FCH PET/computed tomography scan, after the administration of 5-8 mCi (185-296 MBq) at 1 min per frame for 15 min. Delayed static images of 2-3 min per bed position were taken between 45 and 60 min. 3D-VOI's were plotted on parathyroid adenoma, cervical LN and thyroid. Dynamic and static images were interpreted by two expert nuclear medicine physicians independently and the following parameters were calculated for parathyroid adenoma and cervical LN: maximum standardized uptake value (SUVmax), time activity curve for SUVmax, t-peak. Adenoma to thyroid ratio (A/T) and cervical LN to thyroid ratio were calculated for each dynamic and static image.

Results: Fourteen (eight females and six males) patients were included in the study. All patients showed a higher SUVmax in the adenoma and the cervical LN in the early dynamic images as compared with delayed static images. A/T ratio obtained in the dynamic and static images were compared and found to have insignificant difference (P=0.2255). The difference between mean A/T and LN to thyroid ratio was found to be significant (P=0.0117) during the dynamic study.

Conclusion: A possible explanation of higher SUVmax in the dynamic images in adenomas may be due to the increased vascularity/early F-FCH uptake. Results indicate early dynamic imaging could suffice, without the need for a delayed image after 45 min, and this technique could adequately differentiate a parathyroid adenoma from a cervical LN.