Dual-phase 99mTc-MIBI imaging and the expressions of P-gp, GST-π, and MRP1 in hyperparathyroidism.

Abstract

ObjectiveThe aim of this study was to further elucidate the mechanisms of dual-phase technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) parathyroid imaging by exploring the association between early uptake results (EUR), delayed uptake results (DUR), and the retention index (RI) in dual-phase 99mTc-MIBI parathyroid imaging and P glycoprotein (P-gp), multidrug resistance-associated protein 1 (MRP1), and glutathione S-transferase-π (GST-π) expression in hyperparathyroidism (HPT).Patients and methodsPreoperative dual-phase (early and delayed) 99mTc-MIBI imaging was performed on 74 patients undergoing parathyroidectomy for HPT. EUR, DUR, and RI were calculated. P-gp, MRP1, and GST-π expressions were assessed using immunohistochemistry in resected tissue from HPT and control patients. The association between P-gp, MRP1, and GST-π expressions and EUR, DUR, and RI in HPT was evaluated.ResultsThe positive rate of dual-phase 99mT c-MIBI imaging was 91.89% (68/74) and the false-negative rate was 8.11% (6/74). P-gp and GST-π expressions were higher in tissues resected from control compared with HPT patients (47.37 and 81.5%, P<0.05); there was no difference in MRP1. EUR were associated with P-gp and GST-π expressions, and DUR were associated with MRP1 expression. There was a significant difference in MRP1 expression between RI greater than or equal to 0 and RI less than 0. There was no relationship between the sensitivity of dual-phase 99mTc-MIBI imaging and P-gp, MRP1, and GST-π expressions in resected parathyroid tissue. The six false-negative HPT cases consisted of three P-gp (−)/MRP1 (−) tissues, three P-gp (−)/GST-π (−) tissues, and four MRP1 (−)/GST-π (−) tissues.ConclusionAs P-gp and GST-π expressions were higher in tissues resected from control compared with HPT patients, 99mTc-MIBI may wash out faster from normal parathyroid tissue surrounding the lesion compared with the lesion itself, facilitating detection.