Is C-11 Methionine PET/CT Able to Localise Sestamibi-Negative Parathyroid Adenomas?

Patients with primary hyperparathyroidism (pHPT) and a negative preoperative Tc-99 sestamibi (MIBI) scintigraphy are considered to have a higher risk of persistent disease. The aim of this study was to assess whether additional imaging with C-11 methionine positron emission tomography/computed tomography (Met-PET/CT) is able to localise sestamibi-negative hyperfunctioning parathyroid glands.

In 50 patients (38 females, 12 males, age 13-81 years) with pHPT and negative localisation procedures such as ultrasound and sestamibi, a Met-PET/CT was performed before parathyroid surgery. The results of Met-PET/CT were analysed prospectively and compared with intraoperative and histopathological findings. 22% of the patients underwent previous parathyroid and/or thyroid surgery.

Met-PET/CT correctly located a single-gland adenoma in 33 of 45 (73%) patients with pHPT. In 5 patients with multiglandular disease, Met-PET/CT detected at least one hyperfunctional parathyroid gland in 4 patients (80%). In 3 patients with double adenomas, 5 of 6 parathyroids were correctly located. Overall, 40 of 57 (70%) hyperfunctioning glands were identified with Met-PET/CT. Met-PET/CT was false-negative in 12 of 50 (24%) patients and false-positive in only one case (2%). Postoperatively, 48 of 50 patients (96%) were cured.

Additional pre-interventional imaging with Met-PET/CT was able to identify hyperfunctioning parathyroid glands in 74% of patients with pHPT and negative sestamibi scans, thus enabling successful parathyroid surgery.