Causes of ARDS can be intrathoracic or extrathoracic, and this distinction can be inferred on CT imaging
True. Causes of ARDS include both intrathoracic and extrathoracic etiologies. Sometimes, this distinction can be made on CT. One should suspect an extrathoracic cause of ARDS when there is uniform consolidation and ground glass opacity in the lungs with a posterior to anterior gradient of decreasing severity ( Figure 18-10 ). That is, the lungs are densely consolidated in their dependent (posterior) portions, centrally less opacified by ground glass opacity, and normally aerated anteriorly. If the pattern is asymmetric and patchy, one should rather consider an intrathoracic etiology such as pneumonia.
