Localization of parathyroid adenomas using 11C-methionine positron emission tomography

In symptomatic hyperparathyroidism, pre-surgical localization of the suspected site of adenoma is desirable. All widely available techniques may have difficulty in localizing the site. The aim of this study was to determine whether 11C-methionine positron emission tomography (PET) could accurately localize parathyroid adenomas in patients in whom conventional imaging had failed.

Fifty-one patients presenting with hyperparathyroidism, and in whom other imaging techniques had failed to definitely identify the site of adenoma, were reviewed retrospectively after 11C-methionine PET scanning. Patients were followed up by surgical histology, or clinically if surgery was not performed.

11C-Methionine PET scanning was found to have a sensitivity of 83%, a specificity of 100% and an accuracy of 88% in successfully locating parathyroid adenomas. Most false negatives were due to adenomas in the lower mediastinum that was outside the area of scanning.

11C-Methionine PET is a reliable and highly accurate technique for localizing parathyroid adenomas in patients in whom conventional imaging techniques have failed. It is necessary to image to the level of the lower mediastinum.