Which imaging feature is characteristic of ARDS?

The presence of bilateral pulmonary infiltrates is a hallmark imaging feature of Acute Respiratory Distress Syndrome (ARDS). In ARDS, inflammation in the lungs leads to increased permeability of the alveolar-capillary membrane, resulting in fluid accumulation in the alveoli. This process typically manifests on imaging as disseminated bilateral ground-glass opacities and consolidation, which are seen in both lungs.

Bilateral infiltrates reflect the diffuse nature of the lung injury characteristic of ARDS, as opposed to unilateral infiltrates, which may suggest other types of lung pathology such as pneumonia or a localized injury. Normal lung fields would indicate the absence of significant pulmonary pathology, which is inconsistent with ARDS, where changes are expected due to extensive inflammation and fluid accumulation. Interstitial lung disease generally has different radiographic features, often involving a more diffuse pattern of interstitial markings rather than the acute consolidative pattern seen in ARDS.

Thus, bilateral pulmonary infiltrates serve as a key imaging indicator for diagnosing ARDS, distinguishing it from other respiratory conditions.