Use of 131I-toluidine blue in radionuclide imaging of enlarged parathyroid glands.

Parathyroid scintigraphy with 131I-labelled toluidine blue was performed in 40 patients, 30 of whom were operated for suspected hyperparathyroidism. Hyperplastic glands or adenomas could be localized by scintigraphy in 18 of 27 patients who proved to have hyperparathyroidism. The correlation between scintigraphy and operative finding was always correct when the parathyroids weighed more than 2 g. Scintigraphy was correctly negative in one, falsely negative in 6, and falsely positive in 5 of the operated patients. In a group of 10 unoperated patients, scintigraphy was positive in one of the 3 patients with suspected hyperparathyroidism, but negative in the others. Although 131I-toluidine blue is not ideal as a scintigraphic agent for the parathyroids, we are of the opinion that it represents an improvement compared with 75Se-selenomethionine.