Dual radionuclide imaging using a combination of 201Tl with 99mTc-pertecnetate is recognized as a useful procedure in the preoperative localization of parathyroid adenomas. Recently, 99mTc-MIBI scintigraphy has been introduced as an alternative to subtraction scintigraphy. The purpose of this study was to evaluate the role of 99mTc-MIBI dual-phase (early and late imaging) parathyroid scan in the detection and localization of parathyroid adenomas and to compare the results with subtraction scintigraphy and ultrasonography. Eighteen patients that had suspicious clinical or laboratory findings for hyperparathyroidism were included in this study. 99mTc-MIBI imaging and ultrasonography were performed for all patients prior to surgical exploration. A positive 99mTc-MIBI scan for parathyroid adenoma was defined as an area of increased focal uptake that persisted on late imaging. Nine out of 18 patients underwent subtraction scintigraphy, also. 99mTc-MIBI, ultrasonography and 201Tl /99mTc subtraction scintigraphy showed a sensitivity of 94% (17/18) 88% (16/18), and 66% (6/9), respectively. We obtained concordant results for 5 patients with parathyroid adenoma using any imaging modality. 201Tl subtraction scintigraphy correctly detected a parathyroid adenoma, undetected with both MIBI and ultrasonography.
In conclusion, 99mTc-MIBI dual-phase imaging was found more sensitive and accurate for the detection and localization of parathyroid adenomas. 201Tl/99mTc subtraction scintigraphy is considered as a helpful second line imaging modality for patients who have a negative result with 99mTc-MIBI scintigraphy, when there is clinical suspicion of hyperparathyroidism.
Keywords: Primary hyperparathyroidism, parathyroid scintigraphy, 99mTc-MIBI, 201Tl/99mTc-perte chnetate subtraction, ultrasonography