Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lung volumes are low , accounting for bronchovascular crowding . There is an ill - defined opacity in the left cardiophrenic angle , which appears to obscure the left inferior cardiac margin , new compared with exam performed four hours ago . No other focal opacities are identified . Cardiomediastinal and hilar contours are unremarkable . There is no pleural effusion or pneumothorax .
    OUTPUT:
    
New focal opacity in the left lower lobe may represent a focus of atelectasis or aspiration given short interval of development .