Imaging of the normal and affected thyroid in children with emphasis on sonography.

In the past 15 years sonography (US) has become the most important imaging modality for the study of the thyroid gland. Thyroid pathologies are classifiable into congenital, diffuse and nodular diseases. US easily assesses congenital conditions such as agenesis or dysgenesis of the gland, although it may fail in demonstrating an ectopic gland. In diffuse diseases (Graves' disease and Hashimoto's disease) is a useful tool in assessing and subsequently monitoring the course of the disease. In thyroid nodular diseases, US main role is to localize nodules, to differentiate solid from cystic and partially cystic structures, and to look for other clinically unknown nodules in the gland. However it can be difficult to determine with US alone whether a nodule is benign or malignant.