Influence of therapy with iodine-131 on thyroid tissue pattern in colour and power Doppler sonography

The aim of this study was to evaluate the influence of radioiodine therapy on sonographic thyroid patterns using power Doppler (PD) and colour Doppler (CD) sonography in hyperthyroid patients with autonomous nodules (AN) and Graves' disease (GD).

B-mode, colour, and power Doppler sonography, (99m)Tc scintigraphy, and laboratory analyses (free thyronine fT(3), free thyroxine fT(4), thyroid stimulating hormone TSH) were performed in 55 patients (AN = 27, GD = 28) before and 6 months following therapy with (131)I radioiodine therapy (RIT).

In patients with an AN (but not in GD), a significant reduction in thyroid vascularization was subjectively noted following radioiodine therapy on both CD and PD ultrasound (Wilcoxon matched pairs, P < 0.05). The pre-therapeutic grade of hypervascularization in the periphery of autonomous nodules correlated closely with the laboratory parameters of hyperthyroidism. As expected, PD indicated a higher grade of vascularization when compared with CD due to its greater sensitivity to flow.

Radioiodine therapy led to a significant reduction in hypervascularization in patients with AN (but not in GD) corresponding to the normalization of serological values. Comparing CD and PD, PD detected a greater number of vessels. CD and PD are not able to replace scintigraphy and/or laboratory analyses in the management of patients with hyperthyroidism.