Imaging of Aspiration: When to Suspect Based on Imaging of Bacterial Aspiration, Chemical Aspiration, and Foreign Body Aspiration

Aspiration-related syndromes comprise a broad spectrum of diseases affecting the airways and lung parenchyma resulting from inadvertent entry of oropharyngeal or gastric contents into the respiratory tract. The diagnosis can be challenging given lack of self-reported symptoms and unwitnessed or silent aspiration events. Aspiration is a common finding in healthy individuals suggesting that host defenses play a critical role in the pathophysiology. In the absence of strict criterion, a high index of suspicion is necessary based on recognition of established risk factors and identification of characteristic imaging findings. Conditions predisposing to altered levels of consciousness and neuromuscular weakness can lead to dysphagia, impaired cough reflux, and subsequent aspiration. The most salient feature on imaging is the anatomic location of the abnormalities, with the superior segments of the lower lobes and posterior segments of upper lobes involved in the recumbent position, and basilar segments of lower lobes in the upright position. Acute syndromes include pneumonia, pneumonitis, and foreign body aspiration. In the more indolent form of aspiration, bronchiectasis, diffuse bronchiolitis, and interstitial lung disease can develop. A detailed understanding of associated radiographic findings for these syndromes can help to implicate aspiration as the cause for imaging abnormalities and ultimately optimize patient management.