Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lung volumes are low . The heart is probably at the upper limits of normal size . The aorta arch is calcified . The descending aorta is mild to moderately tortuous . Opacities at the lung bases can probably be explained by atelectasis in the setting of low lung volumes . There is no pleural effusion or pneumothorax . Moderate degenerative changes affect lower thoracic and visualized upper lumbar spines .
    OUTPUT:
    
Low lung volumes with patchy densities at the lung bases , most likely due to atelectasis .