Thyroid Doppler ultrasonography and resistive index in the evaluation of the need for ablative or antithyroid drug therapy in Graves' hyperthyroidism.

BACKGROUND AND
PURPOSE: Graves' disease (GD) is the most common hyperthyroid disorder, but the therapeutic strategy for choosing between medical or ablative therapy has not been standardized. Thyroid hypervascularity is an important diagnostic feature in GD. This study collected Doppler ultrasonography data from patients with GD, Hashimoto's thyroiditis, and simple goiter to develop a hemodynamic index for use in the evaluation of when antithyroid drugs (ATDs) should be withdrawn or ablative therapy given in GD.
MATERIAL AND METHODS: Thyroid Doppler ultrasonography was used to measure the resistive index (RI) and pulsatility index (PI) in various thyroid diseases. We studied 88 patients, including 13 untreated GD patients, 14 euthyroid GD patients after withdrawal of ATDs for more than 12 months, 14 euthyroid GD patients with normal thyroid stimulating hormone (TSH) concentrations after regular ATD treatment for 12 months (well controlled), 16 hyperthyroid GD patients with undetectable TSH concentrations after regular ATD treatment for more than 12 months (poorly controlled), 13 Hashimoto's thyroiditis patients, and 18 patients with simple goiters.
RESULTS: The PI and RI were significantly different between patients with untreated (median PI/RI 1.36/0.79) or medically well-controlled (median PI/RI 0.66/0.51) GD, but no significant differences in PI and RI were found between patients with untreated or medically poorly controlled (median PI/RI 1.24/0.74) GD. An RI cut-off of at least 0.7 with undetectable TSH was found to be suggestive of the need for ablative therapy in GD patients who had received regular ATD treatment for more than 12 months, because of its statistically high sensitivity and specificity in all untreated and poorly controlled GD patients. An RI of less than 0.6 with normal TSH was suggestive of the need for withdrawal of ATDs in GD patients receiving regular medical treatment, because of its statistically high sensitivity and specificity in all treated euthyroid GD patients.
CONCLUSIONS: This study has developed an RI-derived hemodynamic index that determines the need for ablative or ATD therapy in patients with GD. A large-scale, prospective study is needed to confirm its clinical value.