Abstract: Objective To evaluate the diagnostic efficacy of technetium-99m methoxyisobutylisonitrile single photon emission/computed tomography (99mTc- MIBI SPECT/CT), 99mTc- MIBI double- phase scintigraphy (DPS) DPS and ultrasound (US) in preoperative localization of hyperparathyroidism (HPT) and explore the factors affecting the diagnostic efficacy of 99mTc-MIBI SPECT/CT. Methods We retrospectively analyzed the data of 104 patients with HPT undergoing surgical resection between January, 2015 and July, 2019. Preoperative 99mTc-MIBI imaging was performed in all the patients, and 82 patients also received US examination preoperatively. Semi- quantitative analysis was used to draw the region of interest and calculate the lesion/ipsilateral deltoid muscle (T/NT) uptake ratio. The sensitivity and detection performance of 99mTc-MIBI SPECT/CT, DPS and US in the diagnosis of HPT patients were compared, and the correlations of the T/NT ratios of parathyroid adenoma (PA) and parathyroid hyperplasia (PH) with the expression levels of COX-2 and Bcl-2 were analyzed. Results The diagnostic sensitivity of 99mTc- MIBI SPECT/CT, DPS and US for HPT was 95.19% (99/104), 91.3% (95/104) and 81.71% (67/82), respectively, demonstrating a significantly higher diagnostic sensitivity of 99mTc-MIBI SPECT/CT than US (χ2=9.59, P=0.008). For PH lesions, 99mTc-MIBI SPECT/CT had the highest diagnostic sensitivity, followed by DPS and then by US (P<0.05), but their sensitivity did not differ significantly for PA (P>0.05). The T/NT ratio in fatty hyperplastic glands was significantly lower than that in fat-free hyperplastic glands (P=0.009). In PA, Bcl- 2 expression was significantly lower in false negative lesions than in true positive lesions (P=0.046), but Cox-2 expression did not show such a difference (P>0.05). In PH lesions, the expressions of Bcl-2 and Cox-2 did not differ significantly between false negative than true positive lesions (P>0.05). Conclusions 99mTc-MIBI SPECT/CT has a high sensitivity for HPT localization, and the T/NT ratio is positively correlated with the lesion volume. An increased expression of Bcl-2 in PA lesions and a decreased cell fat content in PH lesions can facilitate the detection of HPT glands by 99mTc-MIBI SPECT/CT.

Key words: hyperparathyroidism, technetium- 99m methoxyisobutylisonitrile single photon emission computed tomography, semi-quantitative analysis, B-cell lymphoma-2, cyclooxygenase-2