COST-UTILITY OF ROUTINE IMAGING WITH TC-99M-SESTAMIBI IN PRIMARY HYPERPARATHYROIDISM BEFORE INITIAL SURGERY

Tc-99m-sestamibi has been shown to localize parathyroid adenomas effec tively, but controversy continues as to the use of this scan before in itial surgery for primary hyperparathyroidism. We analyzed the cost ut ility of obtaining this study before initial surgery for primary hyper parathyroidism. Twenty-two consecutive patients with primary hyperpara thyroidism underwent dual-phase Tc-99m-sestamibi scan before initial b ilateral neck exploration. Surgical findings were correlated with the results of sestamibi scan. There were 15 women and 7 men, with a mean age of 50.5 years (range, 22-76). Preoperative mean total calcium was 11.74 mg/dL (range, 10-15), ionized calcium was 6.19 mg/dL (range, 5.2 -7.7), and intact parathyroid hormone was 153.5 pg/mL (range, 83.1-551 ). Postoperative mean ionized calcium was 4.56 mg/dL (range, 4.1-5.57) . Twenty sestamibi scans had a positive localization, and 2 scans had no localization. At surgery, 18 solitary adenomas, 3 diffuse hyperplas ias, and 1 patient with four normal parathyroid glands were found. Six teen sestamibi scans were true positive (solitary adenoma), 4 scans we re false positive (2 diffuse hyperplasia, 1 wrong side, and 1 lymph no de), 1 negative scan was true negative (diffuse hyperplasia), and 1 ne gative scan was false negative (adenoma). One patient (four normal gla nds) at the second operation had a supernumerary fifth gland adenoma e xcised from the mediastinum. Preoperative Tc-99m-sestamibi scan did no t-offer any advantage when a complete bilateral neck exploration is pe rformed. Sixteen of (84%) adenomas were correctly localized, but 18 of 19 adenomas were in the neck and were easily found. The 1 ectopic ade noma was not found by scanning or with initial surgery. The 4 of 22 (1 8%) false-positive localizations and the 2 of 22 (9%) negative scans c ontributed nothing to the surgery. Of the 22 localizing sestamibi scan s, surgery was not altered to affect the outcome. At a cost of $550 pe r sestamibi scan and with the error inherent in the scan, it is not co st effective to obtain Tc-99m-sestamibi scan before initial surgery fo r primary hyperparathyroidism.