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CT of Blunt Chest Trauma Scott

R. Kerns1



B. Gay

Although CT is the examination of choice in trauma of the head and abdomen, its role in the evaluation of blunt chest trauma is still evolving. We compared anteroposterior supine chest radiographs with chest and abdominal CT scans obtained over a 2-year period in victims of major trauma. CT proved useful in diagnosing unsuspected chest injuries, showing their full extent, and directing specific interventions to immediately optimize patient care.

Fig. 1.-Si-year-old patient who fell 40 ft (12.2 m). CT scan shows slightly displaced rib fracture (arrow) and associated hemopneumothorax. Thor-

acostomy simulate

tube passing through chest wall can a rib fracture



Wall Injuries

Rib fractures occur in 56% of patients with major blunt chest trauma, but many of these fractures are not shown on the initial radiograph [1]. CT not only can show rib fractures but also reveals complications such as hemothorax and pneumothorax (Fig. 1).

Fig. 2.-33-year-old patient with anterior chest pain after hitting steering wheel. shows asymmetry of medial ends of clavicles, suggesting sternoclavicular dislocation. Superior mediastinum is widened. B, CT scan shows asymmetry is due to displaced sternal fracture (arrow). A retrosternal hematoma A, Radiograph

is present






Received July 10, 1989; accepted after revision August 24, 1989. Presented 1

at the annual


Both authors:Department

of the American Roentgen Ray Society, Box 170, University of Virginia

of Radiology,

New Orleans, May 1989. Health Sciences Center, Charlottesville,

Kems. AJR 154:55-60,


1990 0361 -803X/90/1


© American Roentgen Ray Society

VA 22908. Address



to S. A.


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Sternoclavicular dislocation and sternal fractures may be associated with injury to the heart, great vessels, or tracheobronchial tree. Unlike the supine radiograph, CT can show a retrosternal hematoma (Fig. 2). Although injuries to the heart, great vessels, or tracheobronchial tree are not necessarily associated with a retrosternal hematoma, identification of a hematoma may allow earlier diagnosis and treatment of these injuries. Serious thoracic spine injuries can complicate chest trauma but may produce only minor abnormalities on the chest radiograph. CT not only shows the presence and extent of a spinal injury, it also predicts the degree of instability produced, and can show bony fragments in the neural canal (Fig. 3). Scapular fractures are overlooked or obscured on the chest radiograph in as many as 35% of patients [2]. Injuries severe enough to fracture the well-protected scapula usually produce other injuries, such as rib fractures, pneumothorax, hemothorax, and pulmonary contusion. The axial orientation of CT makes it more sensitive than radiographs in identifying scapular fractures and associated injuries (Fig. 4).




AJR:154, January 1990



Pneumothorax ranks second only to rib fracture as the most common injury in blunt chest trauma [1 ]. A small anteromedial or subpulmonic pneumothorax easily may escape radiographic detection. The presence of even a small pneumothorax is important because artificial ventilation may cause it to enlarge and possibly become a tension pneumothorax. CT identifies twice as many pneumothoraces as the supine radiograph because CT can detect a free pleural edge without the need for an X-ray beam to be tangential to this edge (Fig. 5)[3]. Hemothorax is the most common cause of shock in blunt chest trauma [1]. Blood layers posteriorly in the pleural space in the supine patient and produces a nonspecific density on conventional radiographs. Axial CT images accurately identify and estimate the volume of a hemothorax (Fig. 6). A large hemothorax requires drainage via a thoracostomy tube to improve ventilation and avoid formation of an empyema.

Fig. 3.-27-year-old

aplegia. A, Radiograph








for lower thoracic paravertebral soft-tissue swelling (arrows). B, CT scan shows comminuted vertebral frac-

hire with paraspinal hematoma and bilateral hemothoraces. Note retropulsed fragment in neural canal (arrow).

Fig. 4.-25-year-old patient with pain in left side and back after motor vehicle accident. A, Radiograph shows multiple left rib fractures and pulmonary contusion, but part of left scapula is obscured by ribs and ECG electrode. B, CT scan ture (arrow).








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AJR:154, January 1990





Fig. 5.-29-year-old patient with soft-tissue crepitus after motor vehicle accident. A, Radiograph shows extensive subcutaneous emphysema in neck and chest wall. B, CT scan shows bilateral radiographically occult pneumothoraces (arrows). Note subcutaneous emphysema dissecting along fascial planes.


Fig. 6.-46-year-old dropping


Fig. 7.-18-year-old patient after placement of multiple thoracostomy tubes. A, Radiograph shows that a left pneumothorax (arrows) persists despite apparent adequate placement of tubes. B, CT shows that tubes have been placed p05-

teriorly and cannot drain anterior pneumothorax, which is now under tension as evidenced by meof an ante-


Fig. 8.-65-year-old


with onset

of fever

and leukocytosis 2 weeks after chest injury. A, Radiograph



tube, which was not draining collection. B, CT scan shows


right thoracostomy

right pleural fluid

tube anterior

to locu-

lated pleural fluid collection, which has an enhancing rim. Purulent material and old blood were obtained

with CT-guided


of catheter.


a large


hemothorax and smaller right hemothorax layering posteriorly; both required drainage with thoracostomy tubes.

diastinal shift. Subsequent placement rior tube evacuated the pneumothorax.

patient with back injury and CT scan



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Supine radiographs diagnose only 5% of malpositioned thoracostomy tubes when compared with CT [4]. Malpositioned tubes may leave residual anterior pneumothoraces (Fig. 7), which may enlarge with artificial ventilation, or postenor hemothoraces, which may become infected (Fig. 8). CT can assist in redirecting an existing tube or in the correct placement of an additional tube. Pulmonary


Pulmonary. contusion occurs when local compressive forces cause intraalveolar hemorrhage. Adjacent rib fractures are often seen, more commonly in adults than in children. CT shows pulmonary contusion as scattered, fluffy parenchymal densities subjacent to the area of trauma (Fig. 9). An estimation of the extent of contusion is clinically significant because


AJA:154, January 1990

it is related to the degree of posttraumatic respiratory insufficiency. Atelectasis occurs because of hypoventilation from splinting, adjacent hemothorax, retained secretions, or aspirated debris. Atelectasis also complicates contusion because blood in the alveoli deactivates surfactant. Determining the presence and degree of atelectasis is important because the atelectatic lung is prone to infection (Fig. 10). Shearing forces cause pulmonary laceration with the immediate formation of blood- or air-filled cavities (Fig. 11). Early detection of pulmonary laceration can prevent it from later being confused with the delayed cavitation of a lung abscess caused by infected contusion, atelectasis, or aspiration pneumonitis. Intraparenchymal placement of a thoracostomy tube may occur during resuscitation efforts (Fig. 12). In this intraparen-


Fig. 9.-30-year-old

Fig. 10.-16-year-old patient after motor vehicle accident. CT scan shows peripheral, pleura-based density due to atelectasis. Because of its position in posterior costophrenic sulcus, density was not seen on supine radiograph.

patient with increasing

dyspnea after blow to right chest. CT scan shows multiple alveolar densities consistent with pulmonary contusion. Characteristic peripheral location indicates site most affected by local compressive forces produced during blunt trauma.

Fig. 11.-21-year-old patient after fafi. CT scan shows anterior pneumothorax and large area of pulmonary contusion and atelectasis posteriorly. Additional small pulmonary laceration is seen as air-containing cavity within focal area of confused parenchyma



Fig. 12.-33-year-old patient after placement of thoracostomy tube. A, Radiograph shows tube arcing through right hemithorax but is otherwise unremarkable. B, In addition to anterior heads), CT scan indicates







that tube passes into pulmonary parenchyma. Note pulmonary vessels passing under arc of tube (arrow), proving it is not within a fissure.

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A Fig. 13.-16-year-old patient after high-speed car accident. CT scan shows extensive bilateral pulmonary contusions and hemothoraces, which dominate anterior pneumomediastinum (arrows).

Left subcutaneous



placement of thoracostomy tube rax. Bronchoscopy was normal.





Fig. 14.-31-year-old patient with complete T12/L1 dislocation and paraplegia. A, Radiograph shows widened left paraspinal line (arrows) and questionably widened superior mediastinum. B, CT scan confirms mediastinal hematoma (arrows) along with small bilateral hemothoraces. Findings on aortography, performed to exclude concurrent aortic laceration, were normal. Mediastinal

hematoma was presumed to be due to venous hemorrhage.

for pneumotho-

Fig. 15.-69-year-old obese woman with spine injury. A, Radiograph of supine patient shows widened, poorly defined superior mediastinum with small bilateral apical caps. Radiograph of patient in upright position was unobtainable because of

spine injury. B, CT scan shows that mediastinal

widening is and medially located hemothorax Because clinical concern regarding aortic laceration due

to excessive


remained high, aortography findings were normal.

fat (arrows) (arrowhead).





chymal location, the tube removed, a bronchopleural

Mediastinal Although


fails to function and, if it is not fistula may develop [4].

clinical suspicion the diagnostic

Injuries many


Arterial or venous bleeding adjacent injuries may produce

of pneumomediastinum




dissection of air along the bronchovascular bundle from the alveoli to the mediastinum, pneumomediastinum may be caused by tracheobronchial or esophageal disruption. Occasionally CT will detect pneumomediastinum not shown radiographically. Although the majority of these patients do not have tracheobronchial or esophageal disruption, the presence of pneumomediastinum along with a high clinical suspicion of disruption may indicate the need for bronchoscopy, endoscopy, or contrast esophagography (Fig. 13).

from local great vessel injury or a mediastinal hematoma. If the

of aortic laceration is high, test of choice. If suspicion

aortography is low but

is the

radiograph suggests the presence of a mediastinal hematoma, findings on CT can confirm or exclude a mediastinal hematoma (Fig. 1 4). Aortography may be avoided if CT findings suggest another cause of mediastinal widening, such as excessive mediastinalfat, hemothorax collecting medially (Fig. 1 5), or atelectatic



to the




Hemopericardium is usually caused by venous hemorrhage but also can be caused by cardiac injury. CT can detect hemopericardium before the onset of pericardial tamponade when the anteroposterior supine radiograph suggests enlargement of the cardiac silhouette (Fig. 17).


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Fig. 16.-16-year-old patient run over by a car. A, Radiograph shows widened, poorly defined superior mediastinum, bilateral apical pleural caps, and elevation of minor fissure (arrows). B, CT scan shows that apparent mediastinal widening is actually caused by atelectasis of right upper lobe (arrows). No mediastinal hematoma was present, and aortography was not performed. The patient recovered uneventfully.

REFERENCES 1. Tocino I, Miller MH. Computed tomography Imag 1987;2(3):45-59 2. Harris AD, Harris JH Jr. The prevalence

in blunt chest trauma. J Thorac

and significance

of missed



Fig. 17.-19-year-old hemophiliac hit steering wheel during low-speed accident 2 days before presentation. terior supine radiograph suggested



patient who motor vehicle Anteroposenlargement

of cardiac silhouette. CT scan shows large pericardial fluid collection. At pericardiocentesis approximately 11 of blood was obtained, thought to be due to venous hemorrhage.

fractures in blunt chest trauma. AJR 1988:151:747-750 3. Tocino IM, Miller WH, Frederick PR, Bahr AL, Thomas F. CT detection occult pneumothorax in head trauma. AJR 1984;143:987-990 4. Stark DD, Federle MP, Goodman PC. CT and radiographic assessment tube thoracostomy. AJR 1983;141 :253-258

of of

CT of blunt chest trauma.

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