Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Main pulmonary artery contour is again markedly enlarged . The cardiac , mediastinal and hilar contours appear unchanged . The heart is again moderately enlarged . There is probably a small pleural effusion on the left , although not well depicted , as well as a trace one on the right . Background interstitial abnormality suggests mild vascular congestion but even more striking are confluent opacities in both lower lobes suggesting pneumonia in the appropriate setting , probably more extensive on the right than left , although not entirely specific .
    OUTPUT:
    
Opacities at the lung bases worrisome for pneumonia . Findings also suggesting mild vascular congestion . Persistent moderate cardiomegaly with striking enlargement of central pulmonary arteries , as seen previously .