201Tl scintigraphy in thyroid tumors

In 18 surgical cases of thyroid tumors, the findings of 201Tl scintigraphy were compared with those of macroscopic and microscopic examination of surgical specimens. On scintigraphy, 201Tl was concentrated (hot) in the solid areas of tumors and not in the cystic areas (cold). This suggested the usefulness of scintigraphy in differentiating solid and cystic tumors. With the tendency of 201Tl to being concentrated in tumors with high cellular density, scintigraphy may be useful in differentiating solid or malignant tumors. (Ueda, J.)