Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Pacemaker overlies the left chest wall , leads appear unchanged . Low lung volumes , unchanged . No pneumothorax or pleural effusion is seen . Persistent opacity of the lung bases likely represents atelectasis , although infection ca n't entirely be excluded . No acute osseous abnormalities . Surgical clips in the right upper quadrant may be from prior cholecystectomy .
    OUTPUT:
    
Bibasilar opacities likely represent atelectasis in the setting of low lung volumes although infection can not be entirely excluded . Unchanged appearance from prior examination .