Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac silhouette size is difficult to assess given the presence of a moderate to large left pleural effusion , increased from the prior CT . The aorta demonstrates diffuse calcification and mild tortuosity . There is no pulmonary vascular congestion . The right lung is clear . Left basilar compressive atelectasis is noted . No pneumothorax is demonstrated . There are mild degenerative changes in the thoracic spine . Partially imaged is cervical spine fusion hardware . No acute osseous abnormalities .
    OUTPUT:
    
Moderate to large left pleural effusion , increased compared to the prior chest CT , with compressive atelectasis of the left lung base .