Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Semi-upright portable chest radiograph shows an endotracheal tube in place approximately 3 cm above the carina , which is slightly lower than was seen on the study from earlier the same date . Gastric tube and right - sided PICC appear in unchanged position . All lung lobes are aerated , and there is better aeration in the left retrocardiac region , but some bihilar atelectasis persists .
    OUTPUT:
    
Improved left retrocardiac aeration with some persistent perihilar subsegmental atelectasis bilaterally .