Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low accentuating vascular crowding , stable in appearance from ___ . Diffuse prominent interstitial markings are likely due to overlying soft tissues . Opacity in the right lower lung overlies the spine on lateral view . The mediastinal contour , hila , prominent cardiac silhouette are stable from ___ . No pneumothorax or pleural effusion .
    OUTPUT:
    
Right lower lobe opacity most likely represents atelectasis in the setting of low volumes , less likely pneumonia .