Fig. 5.

40-year-old male patient, RT-PCR-confirmed COVID-19, 5 days since symptom onset. Admission PaO₂/FiO₂ ratio was 310, and d-dimer levels < 300 ng/mL. Due to progressive hypoxaemia, he was managed in the intensive care unit with conscious prone position and high flow nasal cannula, with positive tolerance and evolution. a Axial lung-window CT angiography image shows small patchy areas of ground-glass opacities, with slightly dilated small pulmonary arterial branches (small black arrow). b 5 mm axial reconstruction of a subtraction iodine map shows moderate hypoperfusion with a right-sided predominance (*). The ground-glass opacity in the upper right lobe shows decreased perfusion within the opacity, with a peripheral halo of increased perfusion (black arrow). These findings could be explained by physiological hypoxic vasoconstriction. However, the ground-glass opacity in the upper left lobe shows increased perfusion (white arrow)