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 criterion for parathyroidectomy (PTX), this is known to increase the cure rate and reduce the complication rate. Neck ultrasound and MIBI-scintigraphy are the first-line techniques to detect hyperfunctioning parathyroid tissue, however, they have some limitations including the operator-dependent sensitivity and limited utility in case of a deep-laying or ectopic parathyroid. Recently, it has been shown that parathyroid adenomatous cells are capable of capturing choline, making this molecule a potential tracer in parathyroid. The aim of our study was to evaluate the utility of ¹⁸ Fluoro-choline PET/CT in 43 patients with PHPT candidate for PTX with negative or inconclusive results on conventional imaging. All patients underwent neck ultrasound performed by an expert physician, double tracing MIBI SPECT/CT and ¹⁸F-choline PET/CT. The latter both examinations were perfomed at the same site. Neck ultrasound was negative in 23/43 (53%) and inconclusive in 20/43 (47%) patients. MIBI SPECT/CT was negative in 36/43 (84%) and inconclusive in 7/43 (16%) patients. PET/CT was positive in 30/43 (70%), inconclusive in 3/43 (7%) and negative in 10/43 (23%) patients. Thirty-three patients underwent PTX, 22 mini-invasive approach, 11 open cervicotomy (1 for recurrence of parathyroid cancer, 1 for suspected parathyroid malignancy, 2 for multinodular goiter, 1 for concomitant thyroid malignancy, 4 for negative uptake and 2 for bilateral PET/CT uptake). The intraoperative PTH assay was performed in 29 cases and in all but one (96,5%) demonstrated a reduction greater than 50% of PTH levels from the highest basal value. The histology showed parathyroid adenoma in 28 (84%), parathyroid cancer in 2 (6%), papillary thyroid cancer in one and white cervicotomy in two cases. Of note, the two patients with bilateral uptake had the excision of only one pathological gland since at surgical exploration there was no evidence of other enlarged parathyroid gland. Conversely, one patient with only one abnormal uptake at PET/CT had the removal of two enlarged parathyroid glands that were both adenomas. Thus, 26 of 29 parathyroid lesions were true-positive and 3 were false-positive uptake. Overall, per-lesion sensitivity of ¹⁸F-choline PET/CT was 81%, the positive predictive value was 90% and the accuracy was 75% for all parathyroid lesions. In conclusion, ¹⁸ F-coline PET/TC demonstrated a good diagnostic performance and it might be considered as a valid alternative in patients with negative/inconclusive conventional imaging.