CT and MRI findings of developmental abnormalities and ectopia varieties of the thyroid gland.

Ectopic thyroid tissue may be observed anywhere from the tongue base to the lower neck. It is rarely seen in the mediastinum and abdominal cavity. Computed tomography and magnetic resonance imaging are very sensitive for detection and localization of ectopic thyroid tissue. This pictorial essay presents the radiological characteristics of developmental abnormalities and ectopia varieties of the thyroid gland.