Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is at the upper limits of normal size . The aorta is partly calcified with minimal unfolding . Otherwise , the mediastinal and hilar contours are unremarkable . The lungs appear clear aside from streaky left basilar opacities most suggestive of minor atelectasis or perhaps scarring . The lateral view , however shows a posterior opacity , compatible with atelectasis although infection is not excluded . The bones appear likely demineralized with mild - to - moderate degenerative changes along the mid - to - lower thoracic spine .
    OUTPUT:
    
Left basilar opacity which is compatible with atelectasis although infection is difficult to completely exclude .