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Localization of parathyroid adenomas by (99m)Tc-sestamibi scanning: upper neck versus lower neck lesions.

OBJECTIVE
To assess the diagnostic properties of (99m)Tc-sestamibi scanning (dual-phase technique) in patients with primary hyperparathyroidism and to establish the overall efficacy of this imaging technique for localization of an adenoma.


METHODS
The medical records of all 131 patients who underwent parathyroid scanning in a tertiary care center between January 1997 and December 2002 were reviewed. The surgical findings were used as the "gold standard" for the diagnosis of parathyroid pathologic conditions.


RESULTS
Primary hyperparathyroidism was diagnosed in 87 of the 131 patients (66.4%); of these, 76 underwent surgical treatment. In 44 patients, sestamibi scanning was also done for conditions other than primary hyperparathyroidism. (99m)Tc-sestamibi scanning had a sensitivity of 79.1%, a specificity of 86.7%, a positive predictive value of 88.3%, a false-positive rate of 11.6%, and a false-negative rate of 23.3% for the diagnosis of parathyroid adenoma. Despite the apparent high sensitivity of this scanning technique, only 58.2% of the adenomas were found intra-operatively at the location predicted by the scan. Lesions in the upper neck area were missed more frequently by sestamibi scanning than were those in the lower neck area (13 of 32 versus 1 of 35, respectively) (P<0.05).


CONCLUSION
Preoperative localization of parathyroid adenomas with use of (99m)Tc-sestamibi scanning showed a limited capacity to reveal their precise location. Thus, such scans must be complemented with other studies, such as intraoperative ultrasonography and rapid parathyroid hormone assay, to ensure a successful excision if a limited surgical procedure is planned.