sup(99m)Tc-pertechnetate neck uptake in the evaluation of thyroid function

The neck uptake ratio of sup(99m)TcO4- was measured using a gamma camera and pinhole collimator. The patient was sit 2 m apart from the collimator surface and radioactivity was counted 20 minutes after injection. The whole body count with lead shield (C sub(c)) and without shield (C sub(d)), and natural background count (c sub(bg)) were measured. As the shield was utilized the B filter for conventional thyroidal 131I uptake test (lead plate of 1.3 cm x 10 cm x 10 cm) and it was placed over the anterior neck to cover the thyroid gland at the measurement of (C sub(c)). Then sup(99m)TcO4- neck uptake ratio was calculated as following: A=0.6B - 0.97, B=(C sub(d) - C sub(e))/(C sub(d) - C sub(bg)) x 100. The mean values were 5.3%, 4.5%, 3.1%, 11.2% and 20.7% in the group of euthyroid, hypothyroid, subacute thyroiditis, hyperthyroid state with chronic thyroiditis and Graves' disease, respectively. This method is very convenient and simple to perform following scintigraphy of the thyroid gland with pinhole collimator. (auth.)