Inspiratory CXR AP (upper left) shows increased lucency in the left upper lobe when compared to the right upper lobe while expiratory CXR AP (upper right) shows air trapping in the left upper lobe. Magnified view of the upper lobes (below) better shows a round lesion in the lower portion of the left upper lobe which represents mucous trapped distally to an area of atresia in a bronchus.
Pediatric Imaging 