Are 99mTC-Sestamibi Single Photon Emission Computed Tomography Scan Results Associated to the Parathyroid Cell Type in Primary Hyperparathyroidism?

ABSTRACT

INTRODUCTION: 99mTC-sestamibi scintigraphy (SPECT-CT) is a common imaging modality for parathyroid localization in primary hyperparathyroidism (PHPT). Prior studies have suggested that the cellular composition of parathyroid adenomas influences SPECT-CT imaging results. Other biochemical and anatomical factors may also play a role in false negative results. Therefore, after controlling for confounding variables, we sought to determine whether the histologic composition of parathyroid adenomas is associated to SPECT-CT results in patients with single gland disease causing PHPT. METHODS: A retrospective review of patients with PHPT due to confirmed single gland disease was performed over a 2-y period. A 11 propensity score matching was done between patients with positive and negative SPECT-CT results with regard to demographical, biochemical, and anatomical characteristics followed by blinded pathologic examination of cell composition in the matched pairs. RESULTS: Five hundred forty two patients underwent routine four gland exploration and 287 (53%) patients were found to have a single adenoma. Of those, 26% had a negative SPECT-CT result. There were significant differences between groups with regards to biochemical profile, gland location, and gland size. All of which became nonsignificant after propensity score matching. Adenomas were primarily composed of chief cells, with no difference between groups (95% versus 97%, P = 0.30). In the positive SPECT-CT group, chief cells were the dominant cell type in 68% of the cases, followed by mixed type (13%), oxyphil cells (12%), and clear cells (7%). This was similar to the negative SPECT-CT group (P = 0.22). CONCLUSIONS: While certain patient's clinical characteristics are associated with SPECT-CT imaging results, histologic cell type is not significantly associated.