Postsurgical thyroid remnant estimation by 99mTc‐pertechnetate scintigraphy predicts radioiodine ablation effectiveness in patients with differentiated thyroid carcinoma

Abstract Background. The purpose of this study was to evaluate the relationship between postsurgical neck 99m technetium ( 99m Tc)‐pertechnetate uptake and the rate of successful remnant ablation after radioiodine treatment in patients with differentiated thyroid carcinoma (DTC). Methods. Retrospectively enrolled were 232 patients with DTC who underwent total thyroidectomy and fixed activity ablation with 3.7 GBq 131 I. The 99m Tc scans were performed on all patients before 131 I administration. Thyroid ablation was assessed after 6 to 12 months by thyroid‐stimulating hormone (TSH)‐stimulated 131 I‐WBS and thyroglobulin measurement. The rate of successful ablation, occurrence of radioiodine‐induced thyroiditis, and length of hospitalization were correlated with the 99m Tc‐pertechnetate scintigraphy results. Results. A 99m Tc uptake was significantly lower in ablated versus nonablated patients ( p < .001). High 99m Tc‐pertechnetate uptake, especially greater than 1.4%, predicted a high‐risk of unsuccessful ablation. Higher 99m Tc‐pertechnetate uptake was also related to prolonged hospitalization and the occurrence of radioiodine‐induced thyroiditis. Conclusion. The 99m Tc‐pertechnetate scintigraphy is a simple and feasible tool to evaluate thyroid remnants and to predict radioiodine ablation results in patients with DTC. © 2010 Wiley Periodicals, Inc. Head Neck, 2011