[Tc-99-sestamibi scan in the preoperative localization of abnormal hyperfunctioning parathyroid glands]

Hyperparathyroidism is a relatively frequent condition mostly due to a solitary parathyroid adenoma. Although it has been claimed that surgical exploration is the best way to visualize the abnormal parathyroid gland, several imaging techniques have been proposed to localize it in order to simplify and shorten the surgical procedure. Echography, thalium-technetium scintigraphy, computerized tomography and nuclear magnetic resonance have shown a mean sensitivity of 75% which can be increased to about 90% by combining 2 or more of these procedures. In this study, we evaluated the utility of Tc-99m-sestamibi scintigraphy in 13 patients with hyperparathyroidism (11 primary, 2 secondary). High resolution neck echography was carried out in all of the cases. Cervical scans were obtained 10-15 min and 3 hours after giving an i.v. injection of 25 mCi Tc-99m-sestamibi in all the patients; suppression studies with combined 131-I were also done. Positive scans were obtained in 11 out of the 13 patients. Abnormal parathyroid glands were found and surgically excised in all the cases (10 adenomas, 1 carcinoma, 2 hyperplasias). Echographic localization had a sensitivity of only 33.3%. On the contrary, Tc-99m-sestamibi showed a sensitivity of 56% for the whole group, increasing to 82% in the 11 patients with primary hyperparathyroidism whereas the positive predictive value was of 91% and 90%, respectively. We conclude that Tc-99m-sestamibi is a very useful tool in localizing abnormal parathyroid glands and should be the first choice before reoperation after surgical failure or before the first parathyroid surgery whenever it is desired to shorten the surgical and anesthetic duration.