The role of pre-operative thallium-technetium subtraction scintigraphy in the surgical management of patients with solitary parathyroid adenoma.

Since 1985 we have practised scan directed unilateral cervical exploration for patients with primary hyperparathyroidism (HPT) on the basis of a solitary parathyroid adenoma, and who had a pre-operative thallium-technetium subtraction scintigram demonstrating one focus of activity (positive scan). Between 1985 and 1993, a total of 160 patients with proven HPT and a technically satisfactory scintigram underwent neck exploration. Of these, 96 had positive preoperative scans, 81 (84.4%) of which accurately predicted the site of the tumour subsequently retrieved at operation. Seventy-four (77.6%) with positive scans, and 80 of the entire group, underwent unilateral cervical exploration with removal of a presumed single adenoma. Seventy-eight (97.5%) of these patients were cured of their HPT; two patients demonstrated mild persistent hypercalcaemia. Median operating time was significantly reduced for patients having unilateral as opposed to bilateral operation. Our results suggest that, when positive, thallium-technetium subtraction scintigraphy will accurately predict the site of a solitary parathyroid adenoma in a high proportion of patients and will thus permit a unilateral parathyroid exploration in these individuals. The usefulness of the technique is limited by its low sensitivity for small tumours.