The purpose of this study was to test the usefulness of thallium 201 (Tl-201) thyroid scintigraphy in the detection of thyroid malignancies. Early and delayed Tl-201 scintigraphy was done in 135 patients with a clinically solitary thyroid nodule. There were 64 benign tumors and 71 malignant tumors. Scintigraphy was done 10 minutes (early scan) and 2 hours (delayed scan) after the administration of Tl-201.
With a combination of early and delayed Tl-201 scintigraphy, sensitivity was 57.7% and specificity was 81.2%. Therefore Tl-201 scintigraphy is of limited value for the detection of thyroid malignancies.