CT - Standard & Hi Res Insp/Exp CT
Axial lung window
Axial inspiration
Axial expiration
Standard and high-resolution inspiratory images show mosaic attenuation in both lungs with mild bronchiectasis. The vessels within the darker lung are smaller than in the whiter lung indicating that it is the darker lung that is abnormal. With expiration, the whiter lung becomes even whiter, but the darker lung doesn't change, increasing the density differences between the whiter and darker lung. This pattern of mosaic attenuation and the findings on the expiratory images are diagnostic of air trapping. In a patient with a remote lung transplant, the most likely cause is obliterative bronchiolitis due to chronic rejection.