POSITRON EMISSION TOMOGRAPHY WITH C-11 METHIONINE IN HYPERPARATHYROIDISM

Background. Positron emission tomography (PET) has not been evaluated for preoperative localization and functional characterization of the parathyroid tissue in hyperparathyroidism. Methods. Images of the neck and upper mediastinum of 23 patients with hyperparathyroidism were obtained by PET after intravenous administration of 400 to 800 MBq L-[methyl-C-11]-methionine. The investigation was repeated in six patients after Na-2-ethylenediamine tetraacetic acid infusion, whereby stable 65% to 157% rise in intact serum parathyroid hormone values was attained. Results. Parathyroid surgical procedure revealed single (21 patients) or two enlarged parathyroid glands (two patients) that were characterized as chief cell adenoma (n = 13), hyperplasia (n = 10), or carcinoma (n = 2) and weighed 80 to 6000 mg. Twenty (80%) of these glands were localized by PET. The remaining examinations (20%) were false negative and mainly encompassed small parathyroids in juxtathyroid position. Among 15 patients undergoing parathyroid reoperation true-positive localizations were obtained for 87% of the glands. The images displayed lower tracer uptake in residual thyroid lobes (n = 40), esophagus, and cervical vertebrae. Na-2-ethylenediamine tetraacetic acid infusion failed to enhance parathyroid uptake values. Ultrasonography, computed tomography, technetium-thallium scintigraphy, and venous sampling revealed 25% to 53% of the pathologic parathyroid tissues of the patients undergoing reoperation and was largely complementary to PET. Conclusions. The results suggest that PET may provide novel possibilities for the imaging of pathologic parathyroid glands in hyperparathyroidism.