Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable AP upright chest radiograph obtained . A left IJ tunneled dialysis catheter is again noted with its tip residing in the expected location of the right atrium . Lung volumes are low . Previously noted right PICC line has been removed . Given the low lung volumes , evaluation of the lung bases is limited . There is linear opacity in the left retrocardiac space , likely representing atelectasis . No definite signs of pneumonia or CHF . No pleural effusion or pneumothorax . The heart size can not be readily assessed . Mediastinal contour appears stable with atherosclerotic calcifications along the aortic knob . Bony structures are intact .
    OUTPUT:
    
Basilar atelectasis without definite signs of pneumonia .