Reverse discordant scintigraphy in diffuse goiter.

Abstract

Both Tc-99m pertechnetate and radioactive iodine (I-123 NaI or I-131 NaI) are useful in thyroid scintigraphy. These radiopharmaceuticals yield similar functional information in most patients. Occasionally, however, discordant results have been reported in the literature (warm or hot on the pertechnetate image and cold on the radioiodide image). Most of these reports have concerned the solitary thyroid nodule. A case is presented here with diffusely decreased Tc-99m pertechnetate uptake and normal I-131 NaI uptake in a patient with a diffuse goiter and subclinical hyperthyroidism, so-called reverse discordant behavior.