Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: There has been interval partial clearing of the alveolar infiltrates in the lower lobes . however there continue to be residual patchy areas of alveolar infiltrate lower greater than upper lobe with ill - defined vasculature and mild cardiomegaly . . There is a small right effucstion .
    OUTPUT:
    
improving CHF . Underlying infectious etiology can not be excluded .