The clinical usefulness of dual phase 201Tl thyroid scan for false-negative fine-needle aspiration cytological diagnoses in non-functioning cold thyroid nodules.

We evaluated the clinical usefulness of dual phase 201Tl thyroid scan for 11 patients with false-negative fine-needle aspiration (FNA) cytological diagnoses to detect malignant non-functioning thyroid nodules. Benign FNA cytological diagnoses categorized by experienced pathologists were considered as false-negative diagnoses because the final diagnoses of surgical histopathology were malignant. Dual phase thyroid scan, including an early image and a delayed image, were acquired at 10 minutes and 3 hours, respectively, after 2 mCi (74 MBq) of 201Tl was injected intravenously. Dual phase 201Tl thyroid scan findings were visually interpreted as malignant or benign diagnoses. Dual phase 201Tl thyroid scan could accurately diagnose all of the 11 patients with false-negative FNA cytological diagnoses. We concluded that dual phase 201Tl thyroid scan was very useful in detecting malignant non-functioning thyroid nodules in 11 patients with false-negative FNA cytological diagnoses.