Utility of computed tomography in identifying an ectopic thyroid in infants and pre-school children.

In purpose of identifying thyroid tissue in patients with congenital hypothyroidism during childhood, ultrasonography is usually used as a screening examination, and scintigraphy is performed secondarily. Though these methods are useful, it is not easy to identify the accurate location of thyroid tissue by these methods. We previously reported the utility of computed tomography (CT) in identifying thyroid tissue in four cases of congenital hypothyroidism. The purpose of this study is to investigate whether CT is useful in identifying thyroid tissue, compared to ultrasonography or scintigraphy. Nineteen cases (0 month to 18 years of age) that were suspected to have ectopic thyroid tissue or thyroid agenesis on ultrasonography were examined by CT. CT was useful in diagnosing ectopic thyroid tissue or thyroid agenesis in all the cases, whereas ultrasonography or scintigraphy was less accurate in this purpose in seven cases. Plain CT had a difficulty in identifying thyroid tissue in two cases, in which contrasted image was required. This study showed that CT, especially an enhanced CT, is useful in identifying thyroid tissue, when the gland is not identified in the normal position by ultrasonography.