Technetium-99m tetrofosmin parathyroid imaging in patients with primary hyperparathyroidism

Objective To confirm the clinical significance of Tc-99m-tetrofosmin imagin g for the localization of hyperfunctioning parathyroid glands in patients w ith primary hyperparathyroidism. Methods All patients were imaged with Tc-99m-tetrofosmin at 10 minutes and 2 hours after radiotracer injection, and with ultrasonography (US), compute d tomography (CT), and magnetic resonance imaging (MRI), The parathyroid/th yroid uptake ratio of Tc-99m-tetrofosmin (P/ T uptake ratio) was calculated . Patients Twenty patients with primary hyperparathyroidism were referred to our clinic, underwent surgical neck exploration or mediastinotomy and were diagnosed as having parathyroid adenoma, These patients were investigated f or the preoperative localization by 99mTc-tetrofosmin scintigraphy. Results Tc-99m-tetrofosmin imaging demonstrated focal uptake in 19 out of 2 0 patients with parathyroid adenoma, Two of the lesions were ectopic. US id entified 17 parathyroid glands. CT and MRI initially detected 17 parathyroi d glands. However, two additional parathyroid glands were localized on repe ated CT and MRI in tandem with the results of the Tc-99m-tetrofosmin imagin g. Thus, the sensitivity and specificity of tetrofosmin imaging were 95% (1 9/20) and 95 % (19/20); US, 85 % (17/20) and 94% (16/17); initial CT, 85% ( 17/20) and 94% (16/17); and initial MRI, 88% (17/20) and 94% (16/17), respe ctively, The P/T uptake ratio at 2 hours after tetrofosmin injection was co rrelated with the serum concentration of intact PTH (rs=0.47, p<0.05) and t he resected tumor weight (rs=0.53, p<0.05). Conclusion Tc-99m-tetrofosmin scintigraphy is useful for localization of pa rathyroid adenoma. Tetrofosmin uptake depends on the tumor weight and serum intact PTH levels.