Bronchiolitis (plural: bronchiolitides) is a broad term that refers to any form of inflammation of the bronchioles. It is often used in situations where there inflammation primarily occurs in airways smaller than 2 mm . It can carry variable clinical, functional and morphological expression. Bronchiolar disease may be a primary or a secondary condition.
According to some authors, there is some overlap with the term small airways disease .
Usually not detected at chest radiography but may manifest with nonspecific findings such as ill-defined small or hazy clustered nodules or areas of air trapping characterized by hyperlucency and/or oligemia .
CT - HRCT
The presence of bronchiolitis is best assessed with HRCT. CT features include one of a combination of
- centrilobular micronodules (often seen as tree-in-bud opacities),
- bronchial wall thickening
- bronchiolar dilatation (often referred to as bronchiolectasis)
- mosaic attenuation (and/or air trapping if expiratory imaging is used)
One method of classifying various forms of bronchiolitis is as follows :
- inflammatory bronchiolitis
Exact radiographic features are best discussed under each sub-topic.
Other specific forms according to underlying pathology include: