Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart size is within normal limits . The mediastinal and hilar contours appear unchanged . The previously described left pleural effusion is now markedly decreased . There is no pneumothorax . Minimal left basal atelectasis persists but is improved from before .
    OUTPUT:
    
Status post thoracentesis with minimal residual atelectasis on the left , but no pneumothorax .