15 Pleura and Chest Wall

Fig. 15.1 Anatomical relations of the parietal pleura in the lateral chest wall.

a Schematic diagram: (1) skin; (2) subcutaneous fat; (3) chest-wall muscle; (4) intercostal muscles; (5) ribs; (6) parietal pleura; (7) visceral pleura; (8) lung.

Ultrasound Morphology

Normal appearance. The bony structures of the chest wall (ribs and sternum) are characterized by a high-level surface echo with almost complete posterior acoustic shadowing (15.1a,b). By contrast, the uncalcified costal cartilages allow the complete through-transmission of sound waves ( 15.1c). The parietal pleura lines the inner chest wall, while the visceral pleura invests the lung parenchyma.

The pleura normally appears as a bright, well-defined linear echo called the pleural line. The potential space between the pleural layers cannot be visualized with ultrasound. In dynamic real-time sonography during respiration, the visceral part of the pleural echo can be seen gliding in relation to the stationary parietal part ( 15.1 d).

Positions for scanning. The patient should be examined in a sitting position whenever possible. Generally the ultrasound probe is placed

b Sonographic appearance of the structures. 1 = Subcutaneous fat; 2 = chest-wall muscle; 3 = intercostal muscle; 4 = pleural echo.

intercostally. A subcostal transhepatic and intercostal approach is recommended for subpulmonary and diaphragmatic scanning (Fig.15.2, 15.1e,f). The posterior insertion of the muscular diaphragm (crus) can be defined in the paravertebral region in an upper abdominal transverse scan ( 15.1 g–i). When fluid accumulates in the pleural cavity and abdomen, ultrasound can clearly define the contractions of the diaphragm that occur with respiration ( 15.1j–l). On deep inspiration, a subcostal scan angled toward the head can show variable degrees of hepatic impression by the diaphragmatic crura, which appear as hyperechoic “pseudotumors” in the liver ( 15.1 m–o).

A complete ultrasound examination of the pleura is not possible because the mediastinal and paravertebral pleura cannot be visualized. Additional blind spots exist in the regions of the scapula and left hemidiaphragm.