It remains difficult to pre-operatively differentiate follicular carcinoma and adenoma even under intraoperative investigations including histopathologic diagnosis of frozen sections.
Methods: We retrospectively compared dual phase thallium (Tl-201) thyroid scan and fine-needle aspiration (FNA) cytology to detect follicular carcinoma in 12 patients with cold thyroid nodules. Fine-needle aspiration cytology results were assessed and categorized by experienced pathologists into benign, suspicious, and malignant. Dual phase Tl-201 thyroid scan including an early (10-min) image and a delayed (3-hour) image were acquired after 2 mCi (74 MBq) of Tl-201 was injected intravenously. Dual phase Tl-201 thyroid scan findings were visually interpreted as positive and negative results.
Results: Based on FNA cytologic interpretation criteria, three nodules were diagnosed as benign, five nodules were diagnosed as suspicious, and four nodules were diagnosed as malignant. However, based on dual phase Tl-201 thyroid scan interpretation criteria, all of the 12 nodules could accurately diagnose as malignant.
Conclusions: We conclude that dual phase Tl-201 thyroid scan was more accurate in diagnosing follicular carcinoma when comparing with FNA cytology.