The CT shows areas of mosaic attenuation with a considerably dilated central pulmonary artery in keeping with changes of pulmonary arterial hypertension, probably on a background of recurrent PE.

No expiratory study was performed, the airways appear normal with no features to suggest an obliterative or constrictive bronchiolitis abnormality.

The mosaic pattern is suspicion of changes resulting from severe pulmonary arterial hypertension.

Mosaic attenuation is a non-specific finding, which may be seen in any of the following:

• obstructive small airways disease: low attenuation regions are abnormal and reflect decreased perfusion of the poorly ventilated regions, e.g. bronchiectasis, cystic fibrosis, constrictive bronchiolitis
• occlusive vascular disease (can be termed a mosaic perfusion pattern in this setting 7): low attenuation regions are abnormal and reflect relative oligemia, e.g. chronic pulmonary embolism
• parenchymal disease: high attenuation regions are abnormal and represent ground-glass opacity