Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP and lateral views of the chest . Mediastinal contour is essentially unremarkable and appears smaller when compared to prior from earlier the same day although slightly larger when compared to prior exam from ___ likely due to differences in technique . The contour of the visualized aorta on the current exam is unchanged from remote prior without the irregularity seen on most recent prior . Left greater than right bibasilar atelectasis is identified . No acute osseous abnormalities .
    OUTPUT:
    
No definite acute cardiopulmonary process . Mediastinal contour on prior exam from earlier in the same day was likely due to technique and positioning . Contour of the descending thoracic aorta on the current exam is unremarkable . However if there is clinical concern for dissection CT would be more sensitive for evaluation .