Less Invasive Surgery for Primary Hyperparathyroidism Based on Preoperative ^99mTc-hexakis-2-methoxyisobutylisonitrile Imaging Findings

Purpose. The clinical benefits acquired by introducing hexakis-2- methoxyisobutylisonitrile (MIBI), the reliability of MIBI, and the adequacy of applying less invasive surgeries based on MIBI imaging were retrospectively investigated. Methods. The surgical results before introducing ^99mTc-MIBI scintigraphy (MIBI) in 10 patients with primary hyperparathyroidism were compared with those after introducing MIBI in 22 patients. Results. Surgical failure occurred in two patients (20.0%) before introducing MIBI, and in one (4.5%) after introducing MIBI, thus suggesting that the surgical results improved after introducing MIBI. This was because the diagnosis of ectopic adenoma improved with MIBI. Less invasive surgeries were performed in two patients before introducing MIBI, and in 13 patients after introducing MIBI. Consequently, the operation time decreased significantly. The sensitivity of MIBI, ultrasonography, and computed tomography to adenoma was 100%, 72.2%, and 57.1%, respectively, thus indicating MIBI to have the highest sensitivity. The positive predictive value of MIBI was 85.7%, and all false-positive results were caused by nodular lesions of the thyroid gland. However, the preoperative differentiation of false-positive results could be successfully performed by combining MIBI with neck ultrasonography. Conclusion. The sensitivity of MIBI to adenoma was thus found to be highly satisfactory. As a result, it might be possible to perform less invasive surgeries based on MIBI imaging without any decrease in the surgical results.