Can localization studies be used to direct focused parathyroid operations?

There is considerable controversy today concerning the most appropriate surgical approach for patients with primary hyperparathyroidism. The conventional surgical operation involves a bilateral neck exploration through a collar incision with identification of all parathyroid tissue and removal of abnormal parathyroid glands while the patient is under general anesthesia. The success rate of this operation is about 95% or greater in the hands of an experienced endocrine surgeon. Preoperative localization techniques are generally considered to be unnecessary before initial parathyroid operations. The purpose of this investigation was (1) to evaluate the individual and combined accuracy of ultrasonography and technetium 99m sestamibi scans in localizing abnormal parathyroid glands and (2) to determine whether such scans could be used to direct a focused operation.

We retrospectively studied 338 patients with sporadic primary hyperparathyroidism who had preoperative neck localization studies, ultrasonography and/or technetium 99m sestamibi scans, and parathyroid exploration (238 patients or, reexploration, 60 patients) from January 1996 to April 2000 at the University of California San Francisco/Mount Zion Medical Center. The preoperative localization studies were recorded as true-positive, false-positive, and false-negative and compared with the surgical and pathologic findings and with the outcome of the operation.

All of the abnormal parathyroid glands were correctly identified by ultrasonography in 184 of 303 patients (60.7%) and by technetium 99m sestamibi scanning in 183 of 237 patients (77.2%). The sensitivities of ultrasonography and sestamibi were 65% and 80%, respectively. Among the 202 patients who received both ultrasonography and sestamibi scans, a parathyroid tumor was identified at the same site in 105 (52%) of them. When both techniques identified a parathyroid tumor at the same site, the tests were correct in 101 of 105 patients and the sensitivity increased to 96%.

When both the ultrasonography and sestamibi scans identified the same, solitary parathyroid tumor in patients with sporadic primary hyperparathyroidism, this was the only abnormal parathyroid gland in 96% of the patients. A focused parathyroidectomy could therefore be performed in such patients with an acceptable ( approximately 95%) success rate.