Evaluation of single isotope technetium 99M-sestamibi in localization efficiency for hyperparathyroidism

Regardless of surgical effectiveness, ongoing activity in parathyroid localization in hyperparathyroidism (HPT) is an established enterprise. Sestamibi (MIBI), the most recent new modality, is being assessed in this regard.

Twenty mCI of 99 TC Sestamibi was administered intravenously in patients with prospective HPT. Images were assessed by pinhole and full-field gamma camera at 20 minutes and 2 hours. Dual-phase one isotope only was utilized. Patients were then studied for pathology and MIBI correlation.

Sixty-three cases underwent MIBI scanning, 50, or 79%, of which were due to a single adenoma. Sensitivity showed in 41 of 50 adenomas and was 82% correct. Quadrant localization was 97%. Eleven patients showed hyperplasia with MIBI sensitivity of 82% on a case basis but only 31% for multiglandular disease. Overall MIBI sensitivity is 80%. One false-positive and one true-negative case were observed. All patients achieved eucalcemia. No operative morbidity of significance occurred.

Scanning with 99M Sestamibi dual-phase technique is the preferred mode of parathyroid localization in current practice. It is of assistance in primary HPT, essential in recurrent HPT, and of use in ectopic gland detection. It can support surgical intervention in the marginal HPT patient. Scanning still requires bilateral exploration for complete assessment.