Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Study is slightly limited by underpenetrated technique . Heart size remains mildly to moderately enlarged . The aorta is tortuous with mild atherosclerotic calcifications noted at the aortic arch . Enlargement of the pulmonary arteries bilaterally is similar and suggestive of underlying pulmonary arterial hypertension . Retrocardiac opacity could reflect atelectasis though infection is not completely excluded . Right lung is grossly clear . No pleural effusion or pneumothorax is identified .
    OUTPUT:
    
Limited study due to underpenetration . Patchy retrocardiac opacity , possibly atelectasis , but infection can not be excluded .