These are obtained by g-camera imaging of the anterior neck 20 minutes after intravenous injection of 80MBq 99mTc pertechnetate. 99mTc pertechnetate is trapped but not organified, while radioiodine is trapped and organihed by the thyroid gland. (a) Typical image in Graves' disease with homogeneously increased uptake in an enlarged gland; in this case the left lobe is bigger than the right lobe. (b) Typical appearance in an autonomous toxic nodule (Plummer's syndrome) with suppression of uptake in the remaining normal thyroid. (c) Typical appearance of a toxic multinodular goitre with areas of autonomous toxic nodules separated by areas of nodules with no function and areas of normal tissue whose function has been suppressed.
