Clinical significance of extra-thyroid Tc-99m-pertechnetate uptake before initial radioiodine therapy for differentiated thyroid carcinoma

Objective To analyse the clinical characteristics of extra-thyroid Tc-99m-pertechnetate uptake in order to explore the effect of the phenomenon on radioactive iodine (RAI) therapy for differentiated thyroid carcinoma (DTC) and its clinical significance. Methods This study retrospectively selected patients with DTC and extra-thyroid Tc-99m-pertechnetate uptake. The clinical features, location, location count and extra-thyroid Tc-99m-pertechnetate uptake distribution were analysed, combined with the uptake rate, stimulated thyroglobulin (sTg) level, post-therapy whole-body scan and curative effect. Results A total of 38 patients were enrolled in the study and 65 extra-thyroid Tc-99m-pertechnetate foci were detected. Thirty-four patients showed abnormal Tc-99m-pertechnetate uptake in the lymph nodes (26 of 38; 68.4%), lungs (four of 38; 10.5%) and bones (four of 38; 10.5%). The corresponding uptake rates were 0.2%, 0.2% and 0.8%, respectively. The uptake rate and sTg were significantly positively correlated (r = 0.36). I-131 uptake was found in 36 patients at the Tc-99m-pertechnetate uptake site. The number of iodine uptake foci was significantly higher than that of Tc-99m-pertechnetate uptake foci. The sTg value and pathological staging significantly differed between the excellent and nonexcellent response groups (Z = -2.947 and Z = -2.348, respectively). Conclusion Extra-thyroid Tc-99m-pertechnetate uptake mostly indicated metastases with specific clinical features, which may have prognostic value for the judgment of iodine uptake function and the RAI therapy plan.

Automated summary

The study analyzed the clinical characteristics of extra-thyroid Tc-99m-pertechnetate uptake to explore its impact on RAI therapy for DTC. Results showed that this uptake mostly indicated metastases with specific features, providing prognostic value for iodine uptake function judgment and RAI therapy planning.