Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Patchy and linear left lower lobe opacity has partially cleared since a recent radiograph of several hr earlier . The right lung is clear . There is no pleural effusion or pneumothorax . The cardiac and mediastinal contours are stable . The aorta is tortuous . There is surgical hardware in the right shoulder
    OUTPUT:
    
Rapidly improving left lower lobe opacity favors atelectasis or aspiration over an infectious pneumonia .