Thyroid Remnant Estimation by Tc-99m-Sestamibi Scanning Predicts the Effectiveness of rhTSH-Stimulated I-131 Ablation in Patients With Differentiated Thyroid Carcinoma

Abstract

To evaluate the relationship between postsurgical cervical Tc-99m-sestamibi scan uptake and the rate of successful remnant ablation after recombinant human-thyrotropin (rhTSH)-aided-I-131 ablation in patients with differentiated thyroid carcinoma (DTC). In all, 154 DTC patients who underwent total thyroidectomy and rhTSH-aided remnant ablation with I-131 (3.7 GBq) were enrolled. Tc-99m-sestamibi scans were performed during continuing thyroid hormone administration in all cases. Thyroid ablation was assessed after 6 to 12 months by rhTSH-stimulated I-131-whole-body scan and thyroglobulin measurement. The rate of successful ablation, occurrence of radioiodine-induced thyroiditis, and length of hospitalization were correlated with the Tc-99m-sestamibi scintigraphy results. Tc-99m-sestamibi uptake was significantly lower in ablated versus nonablated patients (P<0.0001). A visually positive scan and a Tc-99m-sestamibi uptake greater than 0.9% predicted a high-risk of unsuccessful ablation, prolonged hospitalization, and the occurrence of radioiodine-induced thyroiditis. Tc-99m-sestamibi scintigraphy is a simple and feasible tool to evaluate thyroid remnants and to predict radioiodine ablation results in patients with DTC.