Clinical usefulness of dynamic study in thyroid scintigraphy with Tc-99m pertechnetate for thyroid nodules

We investigated Tc-99m pertechnetate thyroid imaging for differential diagnosis of malignancy or benignancy. Eighteen patients, each with a solitary thyroid nodule detected by clinical palpation, underwent dynamic study in thyroid scintigraphy with Tc-99m pertechnetate. Radionuclide thyroid angiography was performed after injection of 185 MBq of Tc-99m pertechnetate. A static image at 5 and 30 minute was acquired for 3 minutes. Regions of interest (ROIs) were assigned for thyroid nodule and normal thyroid, and time-activity curves (TACs) were generated from these ROIs. The patterns of TACs were classified as decreased, normal or increased. Eight nodules were classified as increased, 7 as normal, and 8 as decreased. Malignant disease of the increased, normal and decreased nodules were 7, 2 and 0 patients. Benign disease of the increased, normal and decreased nodules were 1, 5 and 8 patients. The results of this study indicated that malignant thyroid nodules would demonstrate a degree of perfusion greater than or at least equal to the normal thyroid tissue. Radionuclide thyroid angiography may provide useful clinical information regarding possible malignancy of a thyroid nodule. (author)