Preoperative localization of parathyroid glands in secondary hyperparathyroidism: correlations between 99mTc-MIBI-SPECT/CT, ultrasound, and pathological characteristics.

Objective: To investigate the association between imaging findings and histopathological characteristics of parathyroid glands in patients with secondary hyperparathyroidism (SHPT).

Methods: Seventy-four glands from 21 patients with SHPT who underwent parathyroidectomy were evaluated for their pathological characteristics. The detection rates of parathyroid glands using ultrasound (US) and 99Tc-MIBI-SPECT/CT (MIBI) were compared. Glands were classified as either US-positive or US-negative, and MIBI-positive or MIBI-negative. Morphological and pathological differences between the positive and negative groups were systematically analysed.

Results: The detection rates for parathyroid glands were 71% with US, 65% with MIBI, and 82% when combining both methods. US and MIBI showed similar localization accuracy in SHPT (P = .38). MIBI-positive glands had significantly larger oxyphil nodules compared with MIBI-negative glands (area: 10.92 mm² vs 3.09 mm², P < .01; area proportion: 61% vs 30%, P = .002), while no significant differences were found in chief nodules. The US-positive group had fewer and smaller chief nodules (number: 2 vs 9, P = .005; area: 1.53 mm² vs 11.08 mm², P = .033) and a higher percentage of oxyphil nodules (74% vs 33%, P = .003) compared with the US-negative group. Thirteen glands undetected by both US and MIBI had smaller oxyphil nodule areas (3.59 vs 13.24 mm²) and lower oxyphil nodule area percentages (25% vs 68%). These pathological features, including adipose infiltration, intra-gland haemorrhage, cyst formation, and calcification, showed no correlation with the gland's imaging results.

Conclusion: US and MIBI had similar value in preoperative localization of SHPT. Parathyroid glands with more and larger oxyphil nodules were more likely to be detected by both MIBI and US.