Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Lungs are hyperexpanded . Multi focal airway centric abnormalities in the mid and lower lungs appear relatively similar to the prior study . However , an ill - defined opacity in the left apex posteriorly is apparently new . Cardiomediastinal contours are stable . No definite pleural effusion .
    OUTPUT:
    
New poorly defined left apical opacities , which could represent an acute bacterial infection or exacerbation of chronic MAC infection . Consider short - term followup radiographs after antibiotic therapy if clinical features are consistent with acute bacterial infection . Alternatively , CT may be considered for more complete characterization .