Bronchiolitis 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 6. 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 5.
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 characterised by hyperlucency and/or oligemia 6.
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 1:
- infective bronchiolitis/infectious bronchiolitis
- bronchiolitis associated with hypersensitivity pneumonitis
- respiratory bronchiolitis/respiratory bronchiolitis interstitial lung disease
- follicular bronchiolitis
- bronchiolitis with associated bronchiectasis/bronchioloectasis
Exact radiographic features are best discussed under each sub topic.
Other specific forms according to underlying pathology include:
- 1. Pipavath SJ, Lynch DA, Cool C et-al. Radiologic and pathologic features of bronchiolitis. AJR Am J Roentgenol. 2005;185 (2): 354-63. AJR Am J Roentgenol (full text) - Pubmed citation
- 2. Hwang JH, Kim TS, Lee KS et-al. Bronchiolitis in adults: pathology and imaging. J Comput Assist Tomogr. 21 (6): 913-9. J Comput Assist Tomogr (link) - Pubmed citation
- 3. Essadki O, Grenier P. [Bronchiolitis: computed tomographic findings]. J Radiol. 1999;80 (1): 17-24. J Radiol (link) - Pubmed citation
- 4. Beigelman-aubry C, Touitou D, Mahjoub R et-al. [CT imaging features of bronchiolitis]. J Radiol. 2009;90 (11 Pt 2): 1830-40. J Radiol (link) - Pubmed citation
- 5. Franquet T, MüLler NL. Disorders of the small airways: high-resolution computed tomographic features. Semin Respir Crit Care Med. 2003;24 (04): 437-44. doi:10.1055/s-2003-42378 - Pubmed citation
- 6. Winningham PJ, Martínez-Jiménez S, Rosado-de-Christenson ML, Betancourt SL, Restrepo CS, Eraso A. Bronchiolitis: A Practical Approach for the General Radiologist. Radiographics : a review publication of the Radiological Society of North America, Inc. 37 (3): 777-794. doi:10.1148/rg.2017160131 - Pubmed