Chest Imaging

Nodule

focal, rounded opacity of varying size, seen on plain radiography or CT. It can be well defined or ill defined. Nodules can be solitary or multiple, or considered to be part of a miliary or nodular pattern of diffuse disease.

Nodules are usually considered to be less than 3 cm in diameter; they have been classified on the basis of their size as small (< 1 cm) or large (³ 1 cm). Micronodule is generally used to describe a nodule 7 mm or less in diameter (micronodule (V:1), Fig. 1). On HRCT, nodules can be classified by their distribution (e.g. perilymphatic, centrilobular, or at random).

RW