대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Tranumatic Pulmonary Contusion with Pneumatoceles

Radiologic Findings

Initial PA chest radiograph shows patchy air-space consolidation in right lung. CT scan shows patchy air-space consolidation in right lung and left lower lobe. Multiple pneumatoceles containing fluid and air are seen in the consolidations. Bilateral pneumothoraces are also noted. 10 days later, air-space consolidation nearly disappeared. Nodular opacity suggesting hematoma is seen in right middle lung field.

Brief Review

Contusion of the lung parenchyma is common in major trauma. The radiographic appearances are those of a diffuse ill-defined air-space filling with patchy, often confluent shadowing in the lungs. Presumably the bleeding into the lung parenchyma must continue for a period of time following the injury, and therefore the changes should wax during that time. In the majority of cases the findings are manifest at the time of the initial examination and show little tendency to increase in severity with subsequent examinations. Radiographic clearing of pulmonary contusion may be relatively rapid, and the signs of contusion have often resolved within 48 hours (1).
Pulmonary contusion is distributed according to the spread of a shock wave and does not localize in a lobar or segmental pattern. The interlobar fissures do not dampen the spread of the shock wave and contusion may be seen on either side of the fissures. Schild et al. (2) imaged experimentally induced pulmonary contusions with CT and plain radiographs. CT detected 100% of contusions immediately after the trauma, whereas the plain films failed to detect 20% of contusions even after sequential examination. Lung contusion in itself is not an indication for CT examination (1).
Pneumatoceles may be encountered in association with pulmonary contusion. Shock waves cause shearing of a portion of the lung parenchyma with escape of air into the resultant laceration (3). This localized internal leak of air plus the retraction of lung caused by its inherent elasticity results in a rounded air space. The pneumatocele may contain a variable quantity of fluid, presumably blood. Pneumatoceles are usually first seen several hours after the injury. A pneumatocele usually does not have a well-defined wall in the early stages following injury. The visibility of a pneumatocele is ordinarily dependent on its size, the fluid it contains, and the surrounding pulmonary contusion (1).
If the entire space of pneumatocele fills with blood, the result is a hematoma. Both pneumatoceles and hematomas resolve, pneumatoceles faster than hematomas. Hematomas may take some months to resolve and for a considerable period may be the only visible sequela of previous trauma. As the surrounding pulmonary parenchymal contusion clears, a hematoma becomes more visible as a circumscribed density mimicking a neoplasm. Pneumothoraces and pleural effusions are a common accompaniment of parenchymal injury and may require chest tube drainage (1).

References

1. Dee P. Chest trauma. In: Amstrong P, Wilson AG, Dee P, Hansell DM eds. Imaging of diseases of the chest. 3rd ed. Mosby 2000:950-955.
2. Schild HH, Strunk H, Weber W, Stoerkel S, Doll G, Hein K, Weitz M. Pulmonary contusion: CT vs plain radiograms. J Comput Assist Tomogr. 1989; 13:417-420.
3. Wagner RB, Crawford WO Jr, Schimpf PP. Classification of parenchymal injuries of the lung. Radiology. 1988; 167:77-82.

Keywords

Lung, Trauma,