Emerging roles for transthoracic ultrasonography in pleuropulmonary pathology

As a result of many advantages, such as absence of radiation exposure, non-invasiveness, low cost, safety, and ready availability, transthoracic ultrasonography (TUS) represents an emerging and useful technique in the management of pleural and pulmonary diseases. In this first part of a comprehensive review dealing with the role of TUS in pleuropulmonary pathology, the examination technique, limits, normal findings, and sonographic artefacts and morphology of the most important and frequent pleural diseases are described. In particular, this first part deals with the capability of TUS in detecting pleural effusion and differentiating pleural fluid from pleural thickening; its usefulness in detecting pneumothorax on the basis of the changes in the artefacts detectable in the normally aerated lung and the appearance of pathologic artefacts; and its role in detecting pleural-based lesions and classifying them into extrapleural, pleural, and parenchymal lesions. Finally, the limits of TUS when compared with computed tomography of the chest are described, highlighting the inability of TUS to depict lesions that are not in contact with the pleura or are located under bony structures, poor visualization of the mediastinum, and the need for very experienced examiners to obtain reliable results.