What is a characteristic finding of pleural effusion in radiology?

Blunting of the costophrenic angles is a characteristic finding of pleural effusion in radiology. When fluid accumulates in the pleural space, it exerts pressure on the diaphragm and thoracic cavity, leading to a typical appearance on chest X-rays. The costophrenic angles, which are the areas where the diaphragm meets the ribs, become less sharp and more rounded due to the presence of fluid. This blunting is a key indicator that there is excess pleural fluid, differentiating it from other conditions that may affect lung visibility on imaging.

In contrast, the other options represent findings associated with different types of pathology. For instance, an air bronchogram is typically seen in cases of pneumonia and indicates the presence of fluid or consolidation in the alveoli surrounding air-filled bronchi. Patchy infiltrates are indicative of lung infections or alveolar abnormalities, while a ground glass appearance is often associated with conditions such as pulmonary edema or interstitial lung disease, indicating partial filling of air spaces or increased density in lung parenchyma rather than pleural effusion. Thus, recognizing blunting of the costophrenic angles is essential for identifying pleural effusions on imaging studies.