Disparate imaging of the autonomous functioning thyroid nodule with 99mTc-pertechnetate and radioiodine.

Four nodules, visualized with 99mTc pertechnetate at 20-60 min., were not visualized with either 123I or 131I at 2-4 hours. Each nodule was demonstrated to have autonomy of function in excess of surrounding normal tissue when imaged with radioiodine after TSH suppression. Rapid turnover of an iodine moiety would seem to explain this phenomenon better then the trapping-only function previously ascribed to lesions with disparate imaging using pertechnetate and iodine radionuclides.