Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are clear without focal opacity , pulmonary edema , pleural effusion or pneumothorax . The borderline enlarged cardiac and normal mediastinal contours are stable . A calcification a left paratracheal region most likely corresponds a calcified thyroid nodule .
    OUTPUT:
    
Chronic borderline cardiac enlargement , exaggerated by low lung volumes .