Abstract
Purpose: Uptake and washout ratios of thallium-201 chloride (201TlCl) were studied to confirm their clinical applicability in the differential diagnosis of benign and malignant follicular lesions of the thyroid. Patients and Methods: Sixty-six patients with follicular tumor of the thyroid underwent preoperative thallium scintigram after an intravenous injection of 2 mCi (74 MBq) of 201TlCl. The early accumulation and washout ratios of 201TlCl were obtained by an online data-processing system. All tumors were surgically resected and histopathologically diagnosed as either follicular adenoma (49 patients) or follicular carcinoma (17 patients). Scintigraphic values in terms of the early accumulation and washout ratios were compared between follicular adenoma and follicular carcinoma. Results and Conclusion: Both the early accumulation and washout ratios were significantly higher in follicular carcinoma than in follicular adenoma. It was concluded that dynamic studies on accumulation and washout rates of 201TlCl might be clinically reliable to differentiate between follicular adenoma and follicular carcinoma.
