Detection of an intrathymic parathyroid adenoma by Tc-99m tetrofosmin: A comparison with Tl-201

A 35-year-old woman who had hyperparathyroidism (increased serum levels of calcium and parathormone) and normal neck US scan, underwent standard Tl- 201/Tc-99m pertechnetate parathyroid scintigraphy with the addition of early and delayed imaging with Tc-99m tetrofosmin. A rounded area of increased uptake of Tl-201 and Tc-99m tetrofosmin, located in the upper left mediastinum, was detectable on raw and Tc-99m subtracted images, which represented an ectopic parathyroid adenoma that was surgically removed and histologically confirmed as an intrathymic parathyroid adenoma. Adenoma detectability was much better with Tc-99m tetrofosmin than with Tl-201 as shown by the higher tumor to background ratio. Such favorable imaging characteristics suggest that Tc-99m tetrofosmin may have the potential to act as a suitable agent for parathyroid scintigraphy.