[Detection and localization of enlarged parathyroid glands in patients with hyperparathyroidism using 99mTc-methoxyisobutylisonitrile (MIBI): a study of subtraction scintigraphy with 99mTc-pertechnetate].

In this study we investigated the detectability of abnormal parathyroid gland(s) by 99mTc-methoxyisobutylisonitrile (MIBI) scintigraphy in patients with hyperparathyroidism. The subjects were 6 patients with primary hyperparathyroidism (PHP) with a single adenoma and 13 patients with renal hyperparathyroidism (RHP) on chronic maintenance hemodialysis. The imaging data of 99mTc-pertechnetate were subtracted from those of 99mTc-MIBI (MIBI-Tc), and number and location of the positive images on scintigrams were compared with those obtained by conventional scintigraphy using 201Tl-Cl and 99mTc-pertechnetate (Tl-Tc). All of the patients underwent surgery, and the number and location of the abnormal parathyroid glands were confirmed. The number of resected parathyroid glands were 6 in PHP and 52 in RHP. The detectability of MIBI-Tc was 83.3% in PHP and 51.9% in RHP, while that of Tl-Tc was 100% and 44.2%, respectively. Although no statistically significant difference in the detectability was found between MIBI-Tc and Tl-Tc, the number of false positives with MIBI-Tc was less than that with Tl-Tc. The detectability of MIBI-Tc depended on the size of the parathyroid gland. The maximal diameter and weight of the smallest parathyroid gland detected were 15 mm and 290 mg in PHP, and 9 mm and 50 mg in RHP. The existence of the thyroid gland did not reduce the detectability of MIBI-Tc. In conclusion, MIBI-Tc was clinically very useful for the detection of abnormal parathyroid glands in patients with hyperparathyroidism.