Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Since prior exam , the PICC has been pulled back . The tip is now in the low SVC . The lung volumes are low , which limits evaluation . There appears to be mild vascular congestion without a definite focal opacity to suggest pneumonia . There is no pleural effusion or pneumothorax . The aorta is unfolded and tortuous , similar to the prior exam . The heart size is within normal limits .
    OUTPUT:
    
Limited exam due to low lung volumes . No definite pneumonia .