Normal anatomy of thymus and anterior mediastinum by pneumomediastinography.

Normal radiographic appearances of the thymus and anterior and superior mediastinum based on 34 pneumomediastinograms performed on myasthenia gravis patients are discussed. Knowledge of (1) end-on shadow of major vessels in the mediastinum, (2) topographic relation between major vessels and bilateral lobes of the thymus, (3) variable shape, size, and uneven outline of the normal thymus, and (4) irregularly distributed mediastinal fat, helps make more precise radiographic interpretation in this region.