Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is normal . Cardiomediastinal silhouette is unremarkable . Mild asymmetry of the hilar structures , with prominent left main pulmonary artery contour is unchanged from prior study . There is subtle increased heterogeneous opacity in the lower posterior lung fields , most clearly on lateral view with possible retrocardiac frontal correlate worrisome for infection . The lung apices are clear . There is no pleural effusion or pneumothorax .
    OUTPUT:
    
Subtle heterogeneous opacity in the lower posterior lung fields most clearly seen on the lateral view , worrisome for infection . Results were discussed over the telephone with Dr . ___ by Dr . ___ at 4 :04 p .m . on ___ at time of initial review .