Localization of an ectopic parathyroid adenoma by double-phase technetium99m-sestamibi scintigraphy

摘要

Double-phase planar scintigraphy using 99mTc-sestamib has been introduced as a means to detect and localize parathyroid adenomas. Focal uptake on both early and delayed imaging is typical of these entities. We report a patient with persistent hypercalcemia following subtotal parathyroidectomy, who was found scintigraphically to have an ectopic parathyroid adenoma. Indeed, the acquisition of an additional planar image centred on the mediastinum allowed the ectopic localisation of adenoma.This case suggests that double-phase parathyroid planar scintigraphy is cost-effective, and often necessary, in the assessment of primary hyperparathyroid patients before surgical re-exploration. Intoduction 99m Tc-sestamibi parathyroid scintigraphy is a means of functional imagery allowing the exploration of the hyperparathyroidy. We report through this work the case of a patient presenting a residual hypercalcemy after subtotal parathyroidectomy and at which the double-phase planar scintigraphy using 99m Tc-sestamibi allowed the description of a mediastinum ectopic hearth. Case report A 50 year old women had a subtotal parathyroidectomy for biological hyperparathyroidy and presented with the persistence of a residual hypercalcemy. The computed tomography and resonance magnetic nuclear imagery were inconclusive sight the post-operative fibrosis.Parathyroid scintigraphy of the neck and upper thorax and/or mediastinum was performed 20 minutes and 2 hours after injection of 740 MBq of technetium 99m-sestamibi. To this end we used a gamma-camera with large field provided with pin-hole and parallel-hole collimators (high résoluion-low energy) intended for mediastinal exploration.The 20 th minute scan showed uptake in a normal appearing thyroid gland as well as uptake in one ovoid area in the upper mediastinum. The 2 nd hour image showed wash out of activity from the thyroid and persistence of activity in the upper mediastinum (Figure.1).