Figure 8 a) Dynamic bronchogram with digital subtraction clearly showing tracheal RUL bronchus, narrowing to the carina and widely patent right and left bronchi. b) Simultaneous DynaCT of airway showing apparent narrowing of left main bronchus (artefact). Extra contrast was injected into the tracheal right upper lobeĀ  bronchus to create an alveolar gram indicating good right upper lobe supply. (the tracheal bronchus is not blind ending). LMB = left main bronchus. RUL = right upper lobe. RML = right middle lobe, RLL = right lower lobe.