Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A single upright portable frontal view was obtained . There is a linear opacity with volume loss and elevation of the left hemidiaphragm at the left base , most likely due to atelectasis . There is mild interstitial prominence bilaterally , although no overt pulmonary edema . There is no definite pleural effusion . There is no pneumothorax . The mediastinal contours are normal . The heart size is mildly enlarged .
    OUTPUT:
    
1 . Linear opacity at the left base with associated volume loss is most likely atelectasis . 2 . No pulmonary edema .