The false-positive parathyroid sestamibi - A real or perceived problem anda case for radioguided parathyroidectomy

Objective To demonstrate that the positive parathyroid sestamibi scan, if correctly i nterpreted and applied, truly represents a parathyroid adenoma, never a "fa lse-positive" scan. Summary Background Data Although the sestamibi scan is widely ordered preoperatively to locate para thyroid adenomas, concern about a false-positive scan often causes surgeons to distrust the results. Tis sues such as thyroid adenomas and lymph nodes have been blamed for false-positive studies, but the radioactivity of thes e presumed false-positive tissues has never been measured. Methods Over an 18-month period, 17 patients were referred for persistent primary h yperparathyroidism after undergoing at least one neck exploration. All pati ents had a sestamibi scan prior to their initial operation that was interpr eted as clearly positive and then. during or after an unsuccessful operatio n, deemed false-positive by the surgeon. At the authors' institution, all p atients underwent repeat sestamibi scintigraphy and were taken to the opera ting room while radioactive for a minimally invasive radioguided parathyroi dectomy (MIRP). Results The authors' sestamibi scans demonstrated the same single focus of radioact ivity displayed on the outside scans, clearly positive. During MIRP, an ade noma was successfully located and removed in ail patients, with confirmatio n of the diagnosis by quantitative differential radioactivity and subsequen t histologic examination. Removal of the radioactive tissue cured all patie nts. Conclusion Intraoperative nuclear mapping permitted identification and removal of para thyroid adenomas in all patients with positive sestamibi scans that had pre viously been labelled false-positive, indicating that each patient would ha ve been cured during their previous operation if radioguided techniques wer e used. Surgeons should be extremely cautious in deciding intraoperatively that a positive sestamibi scan is a false-positive scan.