Thyroid scanning with 131Cs

Scanning of the thyroid gland after the administration of radioactive caesium ((131)Cs) was performed in 45 patients; in 38 of these it had been shown that a thyroid nodule failed to accumulate sodium per-technetate ((99m)Tc) or sodum iodide ((131)I). (131)Cs was concentrated in the nodule to a greater degree than in the paranodular thyroid tissue in seven patients, in five of whom thyroid carcinoma was subsequently identified. In five patients (131)Cs accumulated in both the nodule and paranodular tissue, while in the other 26 no (131)Cs uptake occurred in the nodule. In only one of the latter group was the thyroid lesion malignant. Caesium scanning seems to offer a useful supplementary procedure in the investigation of thyroid nodules.