Advantages of Surgeon-Performed Ultrasound for Parathyroid Adenoma Localization and Commonly Missed Adenoma Locations

Introduction: Ultrasound (US) has become an important modality for parathyroid localization in targeted parathyroidectomy; however, its sensitivity is reported to be higher with surgeon-performed US compared to radiology-performed US. This study aims to enhance awareness of areas where parathyroid adenomas might be missed on US by analyzing the characteristics and locations of adenomas that were not definitively localized on radiology-performed ultrasound but were subsequently identified on surgeon-performed ultrasound.

Methods: This is a retrospective review of prospectively collected data from a tertiary academic institution between 2015 and 2023, featuring 108 patients with primary hyperparathyroidism (121 adenomas) in whom radiology-performed US was non-localizing but surgeon-performed in-office US subsequently detected an adenoma. Locations of the adenomas found by the surgeon were analyzed and correlated with surgical findings. Illustrative images and videos were also recorded.

Results: Among the 108 patients, a single adenoma was identified in 95 patients and two adenomas in 13 patients. The average adenoma volume was 0.31 cm3. Radiology-performed US reported the absence of a parathyroid adenoma in 60 patients (55%) and misdiagnosed the adenoma as a thyroid nodule or lymph node in 36 patients (33%). The predominant location for a missed adenoma was inferior to the lower pole of the thyroid, often in the thymic remnant (41%), followed by posterior to the lower pole, deep in the paratracheal space on the spine (27%). Other overlooked adenomas were situated in classic locations for superior and inferior glands (17% and 13%, respectively), and one was intrathyroidal. Operative findings in 101 patients confirmed surgeon-performed US findings in 98% of single adenoma cases. Additional abnormal glands not detected by the surgeon-performed US were found in four patients.

Conclusions: Diagnostic yield of abnormal glands on ultrasound can be improved by increasing awareness of commonly overlooked locations and routinely scanning into the upper mediastinum and deep in the paratracheal space on the spine.