Dynamic studies of radionuclide uptake by the thyroid can be performed with both 1237 and 99mpe, A comparison study of this phase of thyroid metabolism has begun and, to date, twenty-six patients have had thirty. minute uptake curves determined with both radionuclides. In addition, comparison images have been obtained at 30 minutes with technetium-99m and at 30 minutes and 24 hours with todine-123. One would expect that, at comparable times following intravenous injection, the thyroidal accumulation of iodine would always be higher than with technetium, This has not always been true. at this time to reach any definite conclusions. The series is too small It does seem that the two radionuclides provide complementary information and should help to provide a better understanding of the initial phase of radionuclide uptake by the thyroid. 5001353