Clinical Evaluation of ^<201>Tl-Chloride Scintigraphy in Thyroid Tumor

^<201>Tl-chloride scintigraphy was performed for the purpose of distinguishing cold thyroid nodules by ^<123>I and/or ^<99m>Tc pertechnetate. Included in this study were 45 cases, consisting of 16 of thyroid cancer and 29 of benign lesions. Scans were performed 10 minutes (early scan) and 2 hours (delayed scan) after injection of ^<201>Tl. Early scintigrams showed warm or hot nodules in all cases except benign cystic lesions. Delayed scintigrams showed increased accumulations of radioactivities in a large number of malignant cases and a few cases of adenoma. Delayed scitigraphy might be clinically useful in differentiating malignant thyroid nodules from benign nodules. Positive images of metastatic lesions were visualized in three cases of thyroid cancer.