Trauma is the most common cause of mortality in childhood. Although most fatalities are a result of head injuries, the thorax is often involved in major injuries, including motor vehicle-related trauma. The most common manifestations of thoracic trauma are rib fractures. Injuries of the lungs or mediastinum can be life-threatening. Intentional trauma is an important cause of rib fractures in infants and young children.
Thoracic trauma is classified as penetrating versus nonpenetrating. Specific intrathoracic injuries include contusion; pulmonary laceration; traumatic pneumatocele; hematoma; hemothorax; pneumothorax; tracheobronchial disruption; injury of the thoracic aorta; esophageal perforation; thoracic duct rupture; rupture of the diaphragm; and cardiac injury. Pulmonary laceration is an integral component of the mechanism of injury with pulmonary contusion, pulmonary hematoma, and pulmonary cyst or pneumatocele.1
Pulmonary contusion is the most common lung abnormality in children suffering chest trauma. Pulmonary contusion is extravasation of blood into the lung parenchyma. Typically, radiographic manifestations of pulmonary contusion are present within a few hours of the injury. There is subsequent rapid improvement, with diminished opacification within 1 to 2 days and complete clearing within several days after the injury. In comparison to standard radiographs, CT provides greater sensitivity for the early detection and characterization of pulmonary contusion.2,3
The imaging appearance of pulmonary contusion ranges from homogeneous consolidation to irregular mixed airspace densities (Figures 6-1 and 6-2). Air bronchograms are frequently present. The consolidation does not conform to lobes or segments. Contrecoup injury can result in contusion of the lung contralateral to the trauma. In children, there is a propensity for a pulmonary contusion to be located posteriorly or posteromedially, and to have a nonsegmental crescentic shape. This pattern may be related to the relatively compliant anterior chest wall in children.4
This 10-year-old boy was injured by a 20-foot fall. There is a patchy area of consolidation in the left lower lobe.
An axial CT image of a 5-year-old child who sustained blunt chest trauma during a motor vehicle crash shows a triangular-shaped peripheral focus of homogeneous consolidation in the left lower lobe.
An intraparenchymal hematoma of the lung can occur with either penetrating or nonpenetrating mechanisms of injury. The lesion usually occurs in association with a laceration of the lung. The hematoma is most often located in the region of the greatest injury force. A parenchymal lung hematoma is demonstrated radiographically as a homogeneous, well-circumscribed mass, most often located in the peripheral aspect of the lung. An air–fluid level can occur. There is nearly always a surrounding contusion, which may initially obscure the underlying hematoma. CT offers greater sensitivity and specificity than standard radiographs for the diagnosis of a parenchymal hematoma (Figure ...