Background. Delayed technetium-99m sestamibi single photon emission computed tomography (SPECT) scans were prospectively analyzed in a large series of patients with primary hyperparathyroidism. Methods. Three hundred thirty-eight patients underwent sestamibi-SPECT and were explored. Prospective data included preoperative demographics, clinical, sestamibi, and operative findings, laboratory values, and pathologic and follow-up laboratory results from all patients. Results. Between 1994 and 2000, 287 unexplored patients (85 %) and 51 re-explored patients (15 %) participated: The abnormal parathyroid glands excised from 336 of 338 patients included 299 single adenomas (88 %) and 23 double adenomas (7 %), and 14 patients had multigland hyperplasia (4 %). Sestamibi SPECT correctly lateralized 349 of 400 abnormal parathyroid glands, with an overall sensitivity of 87 %, an accuracy of 94 %, and a positive predictive value of 86 %. Precise localization occurred in 82 % of the abnormal parathyroid glands. Sestamibi sensitivity was similar in unexplored (87 %) and reoperative (92 %) cases; two hundred eighty-six of 299 (96 %) solitary adenomas, 38 of 46 (83 %) double adenomas, but only 25 of 55 (45 %) hyperplastic glands were identified. The mean weight of the true-positive glands (1252 ± 1980 mg) was greater than that of the false-negative glands (297 ± 286 mg) (P < .005). Three patients had persistent primary hyperparathyroidism, in spite of the excision of sestamibi-identified lesions in 2 cases. Follow-up indicated curative resection in 99 % of the unexplored cases and 94 % of the remedial cases. Conclusions. Sestamibi SPECT is highly accurate for the localization of parathyroid adenomas in unexplored and re-explored cases, where it is often the only imaging required. Its sensitivity is limited in multiglandular disease.
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