Preoperative localization of parathyroid lesions in hyperparathyroidism: Relationship between Technetium-99m-MIBI uptake and oxyphil cell content

The aim of this study was to assess the relationship between parathyroid oxyphil cell content and early or late phases of uptake of Tc-99m-MIBI, a radioisotope preferentially retained in mitochondriarich cells. Methods: This study is a retrospective, single-blind analysis of all double-phase Tc-99m-MIBI parathyroid scintigraphy studies performed before surgery in our institution between 1990 and 1995. A total of 18 parathyroid lesions in 14 patients were reviewed. This sample included 11 cases of primary hyperparathyroidism (8 adenomas, 1 adenocarcinoma and 2 hyperplasias) and 3 cases of tertiary hyperparathyroidism secondary to chronic renal failure. Results: Uptake of 99mTc-MIBI in the early phase of scintigraphy was associated with larger parathyroid lesions (1.61 +/- 1.61 ml versus 0.33 +/- 0.27 ml; p < 0.02) and higher serum calcium levels (3.00 +/- 0.41 mM versus 2.67 +/- 0.14 mM; p < 0.02). More importantly, we found that a parathyroid oxyphil cell content greater than 25% was more often associated with a positive uptake of Tc-99m-MIBI in the late phase of the test (positive late uptake in 78% of lesions with a high oxyphil cell content versus 33% in lesions with an oxyphil cell content between 1% and 25% and 0% in lesions with no oxyphil cells; p < 0.04). Conclusion: These findings suggest that the late retention of Tc-99m-MIBI in double-phase scintigraphy is related to parathyroid oxyphil cell content.