CT appearances of the normal and abnormal thymus in childhood.

Computed tomography in 25 children with diseases of the thymus was evaluated to determine which features are the most useful in diagnosing thymic pathology. In each case thymic shape, density, and size, particularly thickness and width, were analyzed and compared with similar data in 71 normal children with no clinical evidence of thymic abnormality. Comparison showed that most thymic diseases altered normal thymic shape and contour, and hence evaluation of gross thymic morphology alone was adequate for recognition of abnormality. Although thymic thickness was a more reliable indicator of disease than width, this measurement was rarely required for diagnosing disease. The attenuation value of the thymus was helpful occasionally in suggesting a specific diagnosis.