Fig. 4: CT and MRI examination of the lung and brain in life-threatening SARS-CoV-2 infections.

a, Comparison between lung tissue from an uninfected person (left) and from a person infected with SARS-CoV-2 (right) in a representative CT scan. In these images, ground-glass opacification (light hazy grey tissue) is seen due to inflammatory responses. ARDS results in fluid accumulation in affected lung tissue independent of cardiac dysfunction (non-cardiogenic pulmonary oedema). Viral infection causes lung injury, leading to loss of gas exchange, atelectasis and hypoxaemia. ARDS is associated with fibrinous organizing pneumonia and alveolar damage. SARS-CoV-2 causes epithelial infection and alveolar macrophage inflammation, and activation and secretion of a range of proinflammatory and chemotactic factors that lead to progressive lung tissue damage. b, A SARS-CoV-2-infected patient’s brain MRI scan image showing the brain regions typically involved in those who develop encephalitis or acute necrotizing encephalopathy. The rims of the lateral ventricles can illustrate contrast enhancement with meningeal involvements (red arrow). The medial temporal lobes (yellow arrows), including the hippocampi, may show hyperintense signals, indicating inflammation that may result from the ‘cytokine storm syndrome’, and hypointense signals that show haemorrhage. Other brain regions including the thalamus, cerebral white matter, brain stem and cerebellum can be involved.