Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A portable supine frontal chest radiograph demonstrates mild cardiomegaly and bronchovascular crowding , which is exaggerated by low lung volumes . The thoracic aorta is generally large and tortuous . Left base opacity is likely atelectasis . There is no edema , appreciable effusion , or pneumothorax .
    OUTPUT:
    
Mild cardiomegaly , exaggerated by low lung volumes . No edema or appreciable effusion .