Equivocal parathyroid technetium Tc 99m sestamibi scan results are likely to demonstrate the correct location for parathyroid adenomas.
Patients with primary hyperparathyroidism prospectively consented to participate in an institutional review board–approved study. The parathyroid technetium Tc 99m sestamibi scan results were classified as positive, negative, or equivocal.
A tertiary private hospital in which university faculty practice.
Technetium Tc 99m sestamibi imaging was performed for 464 patients with primary hyperparathyroidism. Eighty-four of these patients had scan results considered equivocal for unilateral adenomas. The algorithm for this group of patients specified that they should receive an injection with technetium Tc 99m sestamibi prior to parathyroidectomy and that an intraoperative parathyroid hormone (iPTH) level decrease of more than 50% be used to define intraoperative success. Seventy-two patients had postoperative calcium levels measured at least 2 weeks after their surgical procedure and defined the study group. The mean follow-up was more than 6 months.
Main Outcome Measure
Correlation of equivocal scan interpretation with operative findings and biochemical cure of hyperparathyroidism.
Of the 72 patients, 39 underwent unilateral surgical explorations and 33 underwent bilateral surgical explorations; 67 (93%) of the patients were initially cured and 68 (94%) were ultimately cured. In the unilateral group, 38 (97%) of the patients were cured. The 1 failure was associated with a false-positive iPTH level decrease. In the bilateral group, 29 (88%) of the patients were initially cured and 30 (91%) were ultimately cured. Two failures were associated with a false-positive iPTH level decrease and 2 with failure to find the adenoma. Of the 33 patients in the bilateral group, surgical exploration of the opposite side was purely by surgeon choice in 11 cases. Of the other 22 patients, in addition to the 3 failures, 7 had 4-gland hyperplasia, 4 had double adenomas, and 6 had false-negative iPTH level results with iPTH level decreases of less than 50%.
Overall, between 48 (67%) and 54 (75%) of the 72 patients would have been cured with unilateral surgical exploration alone.