It can be difficult to distinguish these three entities. There are two diagnostic hints for further differentiation: - Look at expiratory scans for air trapping - Look at the vessels If the vesses are difficult to see in the 'black' lung as compared to the 'white' lung, than it is likely that the 'black' lung is abnormal. Then there are two possibilities: obstructive bronchiolitis or chronic pulmonary embolism. Sometimes these can be differentiated with an expiratory scan. If the vessels are the same in the 'black' lung and 'white' lung, then you are looking at a patient with infiltrative lung disease, like the one on the right with the pulmonary hemmorrhage. Temporary bronchiolitis with air trapping is seen in: - (post) infection - Inhalation of toxin - Rheumatoid arthritis, Sj?gren - Post transplant - Drug reaction (penicillamine) #Clinical #Radiology #CTChest #MosaicAttenuation #Mosaic #Attenuation #Comparison #RadiologyAssistant