The Added Value of Technetium-99 m Sestamibi Scan in Patients with Primary Hyperparathyroidism and Positive Ultrasound.

Background: Neck ultrasound (US) and Technetium-99 m Sestamibi (MIBI) scan are the most commonly used imaging studies for preoperative localization of parathyroid adenomas. The aim of this study was to determine the added value of MIBI scan and its effect on the operative plan via a hypothetical model where a stepwise approach is conducted and MIBI is considered only after the ultrasound is evaluated.

Methods: Patients who underwent parathyroidectomy for primary hyperparathyroidism (PHPT) between 2012 and 2019 at two tertiary centers were included. Data collected included demographic data, preoperative workup, operative findings and follow-up. The added value of MIBI scans was determined for patients with positive ultrasound.

Results: A total of 513 patients with positive US result and a MIBI scan were included. If a stepwise approach was conducted then MIBI scan would not change the operative plan in 492 (95.9%). Among the remaining 21 patients, MIBI scan would correctly change the ultrasound-based operative plan in only 12 (2.3%) patients, while incorrectly change the plan in 9 (1.8%), resulting in unnecessary exploration of the contralateral side. In patients with sonographic appearance of a parathyroid gland larger than 1.2 cm, MIBI scan would correctly change the operative plan in only 1 of the 287 (0.35%) patients.

Conclusions: Our study suggests that the routine use of MIBI scans may have limited added value in patients with PHPT and a positive neck ultrasound, especially in those with adenoma size larger than 1.2 cm. Positive ultrasound alone may be sufficient for the preoperative localization of parathyroid disease.