PREOPERATIVE LOCALIZATION OF PARATHYROID TISSUE WITH TC-99M SESTAMIBII-123 SUBTRACTION SCANNING

To evaluate the utility of technetium-99m (Tc-99m) sestamibi for visua lization of functioning parathyroid tissue, 14 subjects underwent Tc-9 9m sestamibi I-123 subtraction scanning as part of the preoperative ev aluation for hyperparathyroidism. Informative scans were obtained in 1 3 subjects, including 7 patients with recurrent or persistent hyperpar athyroidism, and correctly identified the location of the hyperfunctio ning parathyroid tissue found at surgery. In all informative patients, hyperparathyroidism was due to adenomatous disease or hyperplasia sec ondary to renal failure. Successful scans were obtained with glands as small as 220 mg. In the lone patient in whom Tc-99m sestamibi scannin g failed to localize hyperfunctioning parathyroid tissue, surgery reve aled a 1700-mg hyperplastic parathyroid neoplasm in the neck. In no ca se did a Tc-99m sestamibi scan suggest parathyroid tissue where there was none. In 1 case, a patient presented with persistent hyperparathyr oidism after 1 neck and a second combined neck and mediastinal explora tion. Tc-99m sestamibi imaging revealed uptake in the periaortic regio n, and a 570-mg adenoma was found in the aortopulmonary window. Using only initial studies, prospective evaluation provided a sensitivity of 78.5% and a positive predictive value of 100%. After repeat studies i n 5 patients, 2 of 3 patients with initially negative results and tech nically deficient scans became positive on restudy. Inclusion of these studies increased sensitivity to 93%. Tc-99m sestamibi I-123 subtract ion scanning appears to be a reliable noninvasive method for preoperat ive localization of hyperfunctioning parathyroid tissue.