A blunted costophrenic (costodiaphragmatic) sulcus on a PA view is most commonly associated with:

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Quizplus · Accepted Answer

Blunting of a costophrenic sulcus is characteristic of most pleural effusions. It occurs less commonly in extremely advanced fibrotic interstitial disease. This is not a radiographic feature of pneumothorax. When the diaphragm is flattened by pulmonary hyperinflation in emphysema, the costophrenic angle (sulcus) becomes less acute but does not have the appearance of fluid filling that sulcus.

A Blunted Costophrenic (Costodiaphragmatic) Sulcus on a PA View Is