Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A single portable frontal chest radiograph was obtained . Lung volumes remain low . Bilateral peripheral interstitial opacities in an apical to basal gradient are similar to prior exams dating back to ___ . Mild cardiomegaly is unchanged . No effusion or pneumothorax is present .
    OUTPUT:
    
Stable appearance of bilateral interstitial opacities .