Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Again seen mild increase in interstitial markings bilaterally which could relate to pulmonary edema , but atypical infection is not excluded . Posterior basilar opacity seen on the lateral view may be relate to overlap of structures although subtle consolidation is not excluded . No pleural effusion or pneumothorax is seen . The cardiac and mediastinal silhouettes are stable and unremarkable . Aortic knob calcification is noted .
    OUTPUT:
    
Mild increase in interstitial markings fairly diffusely bilaterally , could represent mild interstitial edema , but atypical infection not excluded . Posterior basilar opacity seen on the lateral view may relate overlap of structures although subtle consolidation not excluded .