Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable AP upright chest radiograph was provided . Linear left mid lung opacity is unchanged and may represent scarring or platelike atelectasis . There is no pulmonary edema . No evidence of pneumonia . The heart is top normal in size though stable . Mediastinal contour is unremarkable . No large effusion or pneumothorax . Bony structures are intact . Mild AC joint arthropathy is noted bilaterally .
    OUTPUT:
    
Mild cardiomegaly without signs of pulmonary edema .