99mTc-MIBI radioguided surgery for limited invasive parathyroidectomy

We report the preliminary results obtained with the intraoperative MIBI-guided gamma probe in a group of 9 patients with primary hyperparathyroidism (pHPT). These patients were selected for limited invasive parathyroid surgery on the basis of a preoperative imaging protocol consisting of a pertechnetate & perchlorate/MIBI scan combined with neck ultrasonography (US). In the operating room 50-70 MBq MIBI was injected 30 to 45 min before parathyroidectomy. The radioactivity was measured intraoperatively at three sites: parathyroid (P), thyroid (T), and background (B). The P/B, P/T, and T/B ratios were calculated. The T/B ratio was relatively constant (range, 1.5-1.8; mean, 1.6), while a wide variability was observed both for P/T ratio (range, 1.2-2.3; mean, 1.7) and P/B ratio (range, 2.1-4.0; mean, 2.9). At surgery single enlarged parathyroid glands were easily identified by means of intraoperative MIBI-guided gamma probe. Moreover, the gamma probe allowed us to perform a limited 2-2.5 cm neck incision in eight patients affected by parathyroid adenoma. In the remaining patient a parathyroid carcinoma was diagnosed and a bilateral neck exploration was performed. The intraoperative MIBI gamma probe seems to be a useful aid when limited invasive parathyroid surgery is performed.