Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Known right perihilar interstitial abnormality better characterized by prior chest CT is not significantly changed . There is no new consolidation or effusion . The cardiomediastinal silhouette is stable . No acute osseous abnormalities .
    OUTPUT:
    
Interstitial abnormality centered in the right perihilar region not significantly changed since prior CT .