Endocrine Abstracts

¹⁸F-fluorocholine positron emission tomography/X-ray computed tomography (PET-CT) was carried out in our patients with primary hyperparathyroidism (PHPT) and inconclusive preoperative neck ultrasound and ⁹⁹Tc-sestaMIBI scintigraphy to localize abnormal parathyroid glands before surgery. The results were retrospectively evaluated and compared to postoperative histopathological findings. A total of 9 patients (1 man, 8 women) with sporadic PHPT was enrolled with a mean age of 62,2 years, mean preoperative levels of calcium 2.71 mmol/l and parathyroid hormone 124 ng/l. ¹⁸F-fluorocholine PET-CT correctly localized a parathyroid adenoma in 7 patients of 9 (sensitivity 0.77). In one patient, adenoma was successfully found by a surgeon in spite of negative ¹⁸F-fluorocholine imaging (false negative). In 2 patients, ¹⁸F-fluorocholine PET-CT localized 3-4 foci suggestive of parathyroid hyperplasia and/or multiglandular disease. In one of them, only a single adenoma was found. In the other subject, in spite of bilateral cervical exploration with total thyroidectomy, parathyroid adenoma was not found resulting in persistent hyperparathyroidism (false positive). In the present cohort, positive predictive value of ¹⁸F-fluorocholine PET-CT parathyroid imaging was lower than sensitivity due to a few false positive results (0.66). 8 of 9 patients had underlying thyroid disease (thyroid nodules and/or autoimmune thyroid disease). High uptake of ¹⁸F-fluorocholine has been documented in oncocytic thyroid adenoma. In all patients (3 of 9) with inconclusive ¹⁸F-fluorocholine PET-CT imaging either oncocytic thyroid cells or oncocytic metaplasia were found by aspiration cytology or postoperative histopathology. In our study sample, ¹⁸F-fluorocholine PET-CT allowed to correctly localize parathyroid adenomas in 77% patients with previously inconclusive conventional imaging. Underlying thyroid pathology, in particular, thyroid oncocytes, may complicate ¹⁸F-fluorocholine PET-CT parathyroid imaging. Further studies are needed to evaluate ¹⁸F-fluorocholine PET-CT imaging in patients with PHPT and simultaneous thyroid disease.