Preoperative parathyroid localization: Prospective evaluation of technetium 99m sestamibi ANJUM KHAN, MD, SAMEER SAMTANI, MD. WAY M. VARMA. MD. ANDRA FROST, MD. and JOSHUA COHEN, MD. Washington, D.C. Theutilityof preoperative parathyroid localization remains controversial. The gold standard tor Identification of abnormal parathyroid glands Is exploration of the neck by an experienced surgeon. However, both tor the experienced and lessexperiencedsurgeon, It may be desirable to localize the abnormalitybeforesurgery.Sucha sfudywould not only direCt the surgeon to the site of the lesion but also would help reduce unnecessary dissection, the number of negative explorations, and operative anesthesia time. Untortunately, currently used nonlnvallve tech- niques InclUding ultrasonography, thaJlJum-teehnetium subtraction, computed tomography scan, and magnetic resonance Imaging hove had only limited success (35% to 78%) In demonstrating abnormal parathyroid glands. Thirtypatients with proven hyperparathyroidism were enrolled to compare a new Imaging agent, technetium 99m sestamlbl, as an alternative to thallium 201 for subtraction scintigraphy with technetium 99m perfechnetate. Only 14 of 30 patients operated on at George Washington University underwent an Identical surgical ap- proach (exploration of all tour glands) and had complete preoperative calcium and parathor- mone levels, postoperative calcium levels, and total time of surgical procedures to tormulate the basis of this report. The remaining 16 had their surgeries at other Institutions. A surgical approach different from that used at George Washington University and unavailability of postoperative calcium levell and times of surgical procedures from these Institutions necessi- tated deletion of these 16 patients from this report. Technetium 99m sestamlbl-technetlum 99m subtraction scans accurately localized the abnormal parathvroid gland In 13 of 14 patients, as compared with only 9 of 14thallium 201-technetlum 99m pertechnetate subtrac- tion scans. Theseresultssupport technetium 99m sestamlbl scanning as the superior modality for preoperative parathyroid localization. (OTOLARYNGOL HEAD NECK SURG 1994;111:467-72.) Primary hyperparathyroidism is characterized by hypercalcemia with inappropriate secretion of the parathyroid hormone. It is the most common cause of hypercalcemia in the nonhospitalized population and the second most common cause of hypercalce- mia, after malignancy, in hospitalized patients. It occurs in about 1 in every 1000 individuals and 1 in From the Division of Otolaryngology and Head and Neck Surgery (Dr. Khan), Department of Radiology (Dr. Samtani), Division of Nuclear Medicine (Dr. Varma), Department of Pathology (Dr. Frost). and Division of Endocrinology (Dr. Cohen). George Washington University Medical Center. Presented at the Annual Meeting of the American Academy of Otolaryngology-Head and Neck Surgery, Minneapolis, Minn., Oct. 2·6, 1993. Received for publication Oct. 3,1993; revision received March 4, 1994; accepted March 11, 1994. Reprint requests: Anjum Khan, MD, Holy Cross Medical Bldg., 2415 Musgrove Rd., Suite 203, Silver Spring, MD 20904. Copyrigh t © 1994 by the American Academy of Otolaryngology- Head and Neck Surgery Foundation, Inc. 0194-5998/94/$3.00 + 0 23/1/55735 every 500 women older than 45 years. 1 About 85% of patients have a solitary parathyroid adenoma. The remainder have either multiple adenomata (3%) or multigland hyperplasia (12%). Most patients can be evaluated with certainty by documentation of a simultaneous increase in the blood levels of calcium and parathormone (PTH). However, preoperative localization of the abnormal gland by an imaging modality continues to be chal- lenging. Noninvasive techniques currently in use include ultrasonography, thallium-technetium subtraction scintigraphy, computerized tomography (Cf), and magnetic resonance imaging (MRI). These tech- niques frequently yield erroneous results in patients with coexistent thyroid abnormalities (which may occur in up to 30% of the patients with primary hyperparathyroidtsmj.' Thus the utility of preopera- tive localization studies has been questioned, and exploration by an experienced surgeon with direct identification of all glands has been accepted as the 467