Preoperative parathyroid localization: Correlating false-negative technetium 99m sestamibi scans with parathyroid disease

dddObjective/Hypothesis: The recent trend toward minimally invasive directed parathyroid surgery has increased the surgeon's reliance on preoperative parathyroid localization. Technetium Tc 99m sestamibi scanning is generally viewed as the gold standard for preoperative localization, with reported sensitivities of 75% to 100% and specificities of 75% to 90%.(1-3) However, in each reported series there exists a group of patients in whom preoperative localization is either equivocal or negative. Study Design: We focused on a subset of patients from our parathyroid database with false-negative sestamibi (MIBI) scans, in an attempt to elucidate features that could affect these studies. We identified 20 patients with negative preoperative scans and confirmed parathyroid disease. We compared them with 22 consecutive patients with positive scans, correlating the following variables: patient age, gender, concomitant thyroid disease (Hashimoto's thyroiditis, papillary thyroid carcinoma, thyroid adenoma), preoperative parathyroid hormone values, location and number of enlarged parathyroid glands, parathyroid weight, and the relative proportion of chief cells, clear cells, oxyphil cells, and adipose tissue. Methods: Retrospective chart review of clinicopathological and radiological findings. Results. We found that patients with false-negative scans were more likely to have an enlarged parathyroid containing a high proportion of clear cells (P =.01). A trend was seen (P =.1) correlating increased parathyroid fat content and false-negative scans. Conversely, positive preoperative scans were more likely to be associated with a higher percentage of oxyphil cells (P =.02). Univariate analysis for other variables, as well as logistic regression analysis, did not achieve statistical significance. Conclusions: To date, the present study is the largest clinicopathological review of patients with false-negative sestamibi scans. Technetium Tc 99m uptake correlates with parathyroid oxyphil cell content, and false-negative scans can occur with parathyroid glands containing predominantly clear cells.