Assessment of thallium-pertechnetate subtraction scintigraphy in hyperparathyroidism.

Reliable techniques for detecting and localising abnormal parathyroid tissue have been a persistent problem. We have evaluated thallium-pertechnetate subtraction scintigraphy in a prospective study of 40 patients with clinical and biochemical evidence of hyperparathyroidism prior to parathyroid surgery. Four patients were excluded as they were shown to have goitre, making subtraction scanning non-diagnostic. 89% of parathyroid adenomas (totalling 27 glands in 26 patients) and 41% of hyperplastic glands (17 glands in 6 patients) were accurately localised prior to surgery. These included three retrosternal glands, four patients with renal failure and tertiary hyperparathyroidism and five patients who had previously undergone neck exploration. The apparent discrepancy between detecting hyperplastic and adenomatous glands was associated with the smaller size of the former. For both types of gland, scintigraphy successfully located parathyroids 0.6 g or more in weight. These results suggest that this simple and non-invasive method is a useful technique for locating parathyroid tissue before parathyroid surgery.