Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Heart size is at the upper limits of normal . The mediastinal and hilar contours are normal . Low lung volumes . There is crowding of the pulmonary vasculature , likely secondary to low lung volumes . Lungs are clear except for linear bibasilar atelectasis or scarring . No pleural effusion or pneumothorax is seen . There are no acute osseous abnormalities . There are degenerative changes of the visualized spine .
    OUTPUT:
    
There is crowding of the pulmonary vasculature secondary to low lung volumes . No frank edema . Heart size is at the upper limits of normal .