PROSPECTIVE COMPARISON OF DUAL-PHASE TECHNETIUM-99M-SESTAMIBI SCINTIGRAPHY AND HIGH-RESOLUTION ULTRASONOGRAPHY IN THE EVALUATION OF ABNORMAL PARATHYROID-GLANDS

Technetium-99m-sestamibi (MIBI) is a new radionuclide for imaging para thyroid tissue; The purpose of this study was to evaluate parathyroid localization using single radiotracer, dual-phase MIBI scintigraphy an d to compare the results to ultrasonography. Twenty-one patients with hyperparathyroidism underwent dual-phase scintigraphy using 25 mCi MIB I and high resolution ultrasonography before parathyroidectomy. Scan r esults were correlated with size, weight, location, and histopathology of excised parathyroid glands, thyroid abnormalities, and cost. Seven teen patients were female, five had secondary or tertiary hyperparathy roidism, and three had a previous parathyroid exploration, Twenty pati ents (95%) were cured, 14 with a single and 1 with a double adenoma, a nd 5 of 6 patients with generalized hyperplasia. Therewere no false po sitive MIBI scans and-one false positive ultrasound study, despite ass ociated thyroid nodules in 29 per cent of patients. The sensitivity of MIBI and ultrasound in the identification of adenomas was 87 per cent versus 57 per cent (P = 0.046), and the rate of detection of hyperpla stic glands was 44 per cent versus 24 per cent (P = 0.19), respectivel y. There was no correlation between scan results and size, weight, or location of adenomatous glands. The cost of dual-phase MIBI was compar able to that of ultrasound. Dual-phase MIBI is more sensitive than ult rasound in the localization of adenomas-and is the preferable modality for preoperative parathyroid localization. Neither MIBI nor ultrasoun d is effective in localization of hyperplastic glands, underscoring th e importance of routine bilateral neck exploration.