Evaluation of radionuclide imaging and echography in the diagnosis of thyroid nodules.

Radionuclide imaging with both Tc-99m sodium pertechnetate and Tl-201 chloride was studied in 152 patients with thyroid nodules. Ultrasonography also was performed in 81 of those patients. Tc-99m sodium pertechnetate scans demonstrated nodules in 69.7% of 78 differentiated thyroid carcinomas (DC) and 72.2% of 54 thyroid adenomas (Ad). Tl-201 chloride was accumulated in 73.7% of DC and 53.6% of Ad. By combining the Tc-99m sodium pertechnetate and Tl-201 chloride scans, the detectability of the nodules was increased to 90.8% for DC and 88.9% for Ad, respectively. The Tc-99m sodium pertechnetate scans showed better visualization of cystic lesions than did the Tl-201 chloride imaging. The Tl-201 chloride images clearly demonstrated intrathoracic tumor invasions in six cases of carcinoma and two cases of Ad. The Tl-201 chloride scan was also of value in detecting regional lymph node involvement and the recurrence and metastasis after thyroidectomy. The detectability of space-occupying lesions by ultrasonography was 96.3% in 81 patients with thyroid nodules. Ultrasonography differentiated well between solid and cystic lesions. The presence and extent of nodular lesions were detected with radionuclide imaging and ultrasonography in 98.8% of patients. Radionuclide imaging combined with ultrasonography provides a rapid, convenient, and useful method for the localization and visualization of thyroid tumors.