Scheme 1.

The SARS-CoV-2 virus affects the nervous and respiratory systems. Sketch illustrating brain ¹H MRI (top) and hyperpolarized ¹²⁹Xe gas lung MRI (bottom). The top schematic illustrates the segmentation and normalization of brain ¹H MRI. The bottom schematic shows two generations of lung respiratory airways of the Weibel lung model, with the main morphometric parameters including internal radius (r), external radius (R), and depth of alveolar sleeve (h). The diagram of the gas–blood exchange region of the alveoli is shown in the lower illustration. The total septal thickness, xenon gas exchange time constant, and hematocrit are assigned as d, T, and Hct, respectively.