Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiac silhouette is mild to moderately enlarged . Mediastinal contours are unremarkable . No large pleural effusion or pneumothorax is seen . Overlying the posterior lateral left seventh rib , there is a subtle rounded opacity measuring approximately 6 mm , unclear whether artifactual , osseous , or possibly pulmonary nodule . This could be further assessed on nonurgent chest CT . No further consolidation is seen .
    OUTPUT:
    
Cardiomegaly . Subtle rounded 6 mm opacity projecting over the posterior lateral left seventh rib unclear whether artifactual , osseous or possibly pulmonary nodule . This could be further assessed with shallow oblique radiographs or chest CT .