We assessed the usefulness of dual phase 201Tl thyroid scan for equivocal fine-needle aspiration (FNA) biopsy results to differentiate malignant from benign lesions. The findings of the dual phase 201TI thyroid scan were compared with those of surgical histopathology for 27 patients with cold thyroid nodules. The FNA results were assessed and classified by experienced pathologists equivocal ENS results. Dual phase thyroid scan, including an early image and a delayed image, were acquired 10 minutes and 3 hours, respectively after mCi (74 MBq) of 201TI was injected intravenously. Dual phase 201Tl thyroid scan findings were visually interpreted as positive or negative results. Based on the final diagnoses of the surgical histopathology results, the dual phase Tl thyroid scan showed a sensitivity, specificity, and accuracy of 100%, 90%, and 96%, respectively. We concluded that dual phase Tl thyroid scan was very helpful in differentiating between benign and malignant thyroid nodules when FNA results were equivocal.
