CT images in experimental lung injury—muscle paralysis vs. spontaneous breathing. Both dynamic CT images of the same anatomical, sagittal level at end-expiration are shown to compare the end-expiratory lung volume and the shape of the diaphragm. CT images are colored according to their Hounsfield units densities. The black lines indicate the diaphragm at end-expiration. These dynamic CT images were continuously taken after injection of neuromuscular blocking agent, without any change in ventilatory settings. Spontaneous breathing effort restored the end-expiratory lung volume due to diaphragmatic muscle tone. Once diaphragm was paralyzed, diaphragm shifted to cranial direction, resulting in large collapse in dorsal lung regions. Note that this happened because inadequate (low) PEEP was applied.