Endocrine Abstracts

Primary hyperparathyroidism (PHPT) is a common endocrine disease mainly caused by a single parathyroid adenoma. Although the localization of the parathyroid adenoma is not a surgical criteria for parathyroidectomy, this is known to increase the cure rate of PHPT and reduce the complication rate. Neck ultrasound and MIBI-scintigraphy are the first-line localization techniques to detect parathyroid adenomas, however, they have some limitations including the operator-dependent sensitivity and limited utility in case of a deep-laying or ectopic parathyroid. Scintigraphy is better for ectopic localizations but its sensitivity remains suboptimal. Evidence has recently emerged that parathyroid adenomatous cells are capable of capturing choline similarly to what occurs in prostate cancer, making this molecule a potential tracer in parathyroid. We conducted a monocentric study at theUniversity Hospital of Pisa in order to evaluate the utility of ¹⁸Fluoro-choline PET/CT in 20 patients with PHPT candidates for surgery and with negative or inconclusive conventional imaging. All patients underwent a neck ultrasound performed by an expert physician in parathyroid disease and a double tracing MIBI SPECT/CT. Neck ultrasoundwas negative in 15/20 patients and uncertain in 4. SPECT/CT was negative in 18/20 and uncertain in 2 patients. Therefore, 18F-choline PET/CT (with early and late scans and without iodinated contrast) was performed in the whole group. A dosimetric study was done: 18F-choline PET/CT effective dose was 8.09 mSv. Twelve patients (60%) were positive, 4 (20%) inconclusive and 4 negative. Eleven patients underwent surgical removal of the lesion detected at PET/CT, of which eight with mini-invasive approach and three with an open cervicotomy due to a concomitant thyroidectomy for non toxic multinodular goiter. In all cases histology showed a parathyroid adenoma (mean size 7,3 cc, range 0.4–33.5 cc). An intraoperative PTH assay was performed in 9 cases and in all demonstrated a reduction greater than 50% of PTH levels from the highest basal value. Disease cure was confirmed in all patients after 1 month post-surgery and no surgical complications were recorded. In our experience, therefore, 18F-coline PET/TC has demonstrated a good diagnostic performance and a valid alternative in patients having negative/inconclusive conventional imaging. Furthermore, it has allowed us to avoid bilateral cervical exploration in the patients. Finally, compared to four dimensional (4D) CT, another emerging imaging method for parathyroid glands, 18F-coline PET/CT exposes the patients to less radiation (CT 4D effective dose is at least 27 mSv) and does not require the use of iodine contrast.