Artery-to-bronchus ratio Normally the vessels in the upper lobes are smaller than the accompanying bronchus with a ratio of 0.85 (3). At the level of the hilum they are equal and in the lower lobes the arteries are larger with a ratio of 1.35. When there is redistribution of pulmonary blood flow there will be an increased artery-to-bronchus ratio in the upper and middle lobes. This is best visible in the perihilar region. On the left a patient with cardiomegaly and redistribution. The upper lobe vessels have a diameter > 3 mm (normal 1-2 mm). Notice the increased artery-to-bronchus ratio at hilar level (arrows). #Clinical #Radiology #CXR #CHF #Vascular #Engorgement #RadiologyAssistant
