Definition

Epidemiology

Pulmonary contusions and lacerations represent different degrees of damage to the pulmonary parenchyma; these injuries account for 30–60% of all chest trauma Main causes in everyday life include: Motor vehicle accidents (about 75% of cases) Falls from a great height (18%) Occupational accidents (7%) Rarely, stab or gunshot wounds (depending on local environmental factors).

Etiology, pathophysiology, pathogenesis

A distinction is made between blunt and penetrating chest trauma, depending on the mechanism of injury Acceleration/deceleration forces predominate in severe chest trauma Variants include blast injuries, which involve a shock wave Shock wave trauma leads to severe tears along the air–tissue interfaces There is a risk of air embolism, and prompt artificial respiration is required.

Imaging Signs

Modality of choice

Radiographs CT in severe chest trauma and multiple trauma.

Radiographic findings

Homogeneous opacity with an ill-defined border Laceration is distinguishable from contusion only by the presence of pneumatoceles or dense hematoma Findings manifest themselves within hours of the injury Contusions resolve within days; lacerations heal in weeks to months.

CT findings

A contusion appears as an ill-defined minimally invasive area of increased density resembling a ground-glass opacity Lacerations are denser and more inhomogeneous Air inclusions with air–fluid levels are consistent with traumatic pneumatoceles.

Clinical Aspects

Typical presentation

Pulmonary contusions and lacerations are usually clinically asymptomatic Gas exchange is impaired only where there is extensive parenchymal damage with associated injuries (unstable chest, pneumothorax, hemothorax) Blast injuries are invariably associated with respiratory insufficiency.

What does the clinician want to know?

Extent of injury Associated injuries requiring treatment (hemothorax, pneumothorax, tension pneumothorax, unstable chest, aortic rupture, rupture of the diaphragm).

Fig. 12.1 Multiple trauma in a 16-year-old boy.

a The plain chest radiograph shows coarsely nodular to patchy densities over both lungs.

b The CT scan allows better differentiation between the contused areas (arrows), and the lacerations with pneumatoceles (open arrows).

Fig. 12.2 Multiple trauma. The CT scans show a right anterior pneumothorax. Contused areas appear as ill-defined areas of nodular opacification (arrow), and hematomas from lacerations as denser sharply demarcated focal lesions (open arrow).

Tips and Pitfalls

In contrast to CT, less extensive associated pleural injuries (pneumothorax or hemothorax) are easily overlooked on plain chest radiographs Such injuries usually do not require treatment.

Selected Reference

Schnyder P, Wintermark M. Radiology of blunt trauma of the chest. Berlin: Springer; 2000

Definition

Epidemiology

Aortic ruptures occur in about 1–2% of all cases of chest trauma (> 80% are fatal) Traffic accidents are the most common cause.

Etiology, pathophysiology, pathogenesis

Acceleration/deceleration forces predominate in severe chest trauma Intimal flap Intramural and/or periaortic hematoma.

Imaging Signs

Modality of choice

CTA.

Radiographic findings

Abnormal widening of the upper mediastinum (> 8 cm) in combination with signs of a mass (trachea and esophagus shifted to the right; left main bronchus is also shifted) High negative predictive value where plain chest radiograph is normal (98%).

CTA findings

Aortic rupture on CTA appears as an abrupt change in caliber Abnormal aortic contour Intimal flap Intramural and/or periaortic hematoma.

Clinical Aspects

Typical presentation

Cardinal symptom of aortic rupture is shock, a sign of which may be a difference in blood pressure between the right and left arms or between the upper and lower halves of the body.

What does the clinician want to know?

Confirm and localize or exclude Hemothorax Associated injuries.

Differential Diagnosis

Tips and Pitfalls

Pulsation artifacts can mimic aortic dissection (pulsation artifacts change direction and location in every slice).

Fig. 12.3 Contained aortic rupture in a 40-year-old man with multiple trauma.

a The plain chest radiograph shows widening of the upper mediastinum. The knob of the aorta is no longer clearly distinguishable although the contour descending aorta still is. The left main bronchus is elongated and displaced. There is slight tracheal shift.

b, c CT demonstrates the aortic rupture at a typical location distal to the origin of the subclavian artery, with an intimal flap. There is an associated periaortic hematoma.

Selected Reference

Wintermark M, Wicky S, Schnyder P. Imaging of acute traumatic injuries of the thoracic aorta. Eur Radiol 2002; 12: 432–442