Postsurgical thyroid remnant estimation by (⁹⁹m) Tc-pertechnetate scintigraphy predicts radioiodine ablation effectiveness in patients with differentiated thyroid carcinoma.

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 ¹³¹I. The (⁹⁹m) Tc scans were performed on all patients before ¹³¹I administration. Thyroid ablation was assessed after 6 to 12 months by thyroid-stimulating hormone (TSH)-stimulated ¹³¹I-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.