Transthoracic ultrasound.

Sonography (US) has inherent limitations for thoracic imaging because sound waves are reflected by bone and air space (such as in lung parenchyma). However, US is less expensive and more convenient than computed tomography (CT) or magnetic resonance imaging (MRI); it provides immediate information with real-time imaging, and can give information not available from a standard radiograph. This review describes the utility and limitations of US and compares US with radiography.