Association of Histological Findings with Tc-99m Sestamibi Parathyroid Imaging in Hyperfunctional Parathyroid Gland

Abstract

Background: Hyperthyroidism is a relatively common disorder that results from increased production of parathormone. Tc-99m sestamibi (MIBI) scanning is used for localization of abnormal parathyroid gland, with high reported sensitivities. However, there exists a group of patients in whom MIBI scan is either equivocal or negative. Objectives: The aim of this study was to see association of the histological features of pathologic parathyroid gland with MIBI scan in hyperfunctional parathyroid gland. Methodology: This retrospective study was conducted with primary hyperthyroidism who underwent MIBI scan. The data were collected from the record from January 2012 to December 2014 for a period of two years. All patients underwent parathyroid surgery followed by histopathological examination. According to oxyphil cell distribution patients are divided in three groups. Group I comprised of >25.0% oxyphil cell; group II included the 25 to 75% oxyphil cell and group III included >75% of oxyphil cell. Result: A total 56 patients with hypercalcaemia and high serum parathyroid hormone (PTH) level were studied. Mean age was 41.3(±19.8) years with a range of 21 to 63 years. MIBI scan was true positive in 34(60.7%) cases and false negative in 22(39.3%) cases. In group I MIBI scan was true positive in 4(36.3%) cases and false negative in 7(63.7%) cases. In group II MIBI scan showed positive in 17(62.9%) cases and negative in 10(37.1%) cases. In group III out of 18 patients 13(72.2%) showed MIBI scan positive whereas, 5(27.8%) showed negative scan. The sensitivity was 36.3% in group I whereas, 62.9% and 72.2% in group II and group III respectively. Conclusion: Based on these findings, it could be say that Tc-99m setamibi uptake correlate with parathyroid oxyphil cell content, and false negative scan can occur with parathyroid glands containing predominantly clear cell.