Imaging in chest trauma

Imaging the chest in traumaImaging the chest in trauma

Chest traumaChest traumaBlunt

Penetrating

Trauma Chest RadiographTrauma Chest Radiograph

Usually AP, often supine, frequently in poor inspiration.

CT ChestCT Chest

Fractures and DislocationsFractures and DislocationsSpineRibsClaviclesSternumShoulders

Spine InjuriesSpine Injuries

Loss of alignment, fractures and paraspinal hematoma.

Rib FracturesRib Fractures

Indicator of underlying pleura, lung, liver, spleen, kidney injuries.

Flail ChestFlail Chest

Multiple rib fractures, especially if individual ribs fractured more than once, may cause paradoxical motion.

Associated pulmonary contusion.

Clavicle InjuriesClavicle Injuries

Sterno-clavicle joint dislocationSterno-clavicle joint dislocation

Sterno-clavicle dislocation: CTSterno-clavicle dislocation: CT

Shoulder InjuriesShoulder Injuries

dislocations and scapula fractures

CT Needed if Scapula Fracture SeenCT Needed if Scapula Fracture Seen

AIR where it shouldnAIR where it shouldn’’t bet bePneumothoraxPneumomediastinumSubcutaneous emphysemaSystemic venous air embolismPneumopericardiumPneumoperitoneum/retroperitoneum

pnxpnx

PNEUMOTHORAX: CTPNEUMOTHORAX: CTMuch more sensitive

Even a small traumatic pneumothorax is important, especially if patient mechanically ventilated or going to OR: A simple pneumothorax can be converted into a life- threatening tension pneumothorax.

PNEUMOTHORAX: CTPNEUMOTHORAX: CT

Pneumothorax: SimplePneumothorax: SimpleErect AP/PA view bestVisceral pleural lineNo vessels or markingsVariable degree of lung collapseNo shift

PNEUMOTHORAX: SimplePNEUMOTHORAX: Simple

PNEUMOTHORAX: TensionPNEUMOTHORAX: TensionErect AP/PA view bestShift of mediastinum/heart/trachea away

from PTX sideDepressed hemidiaphragmDegree of lung collapse is variable

PNEUMOTHORAX: TensionPNEUMOTHORAX: Tension

PNEUMOTHORAX: SupinePNEUMOTHORAX: SupineSupine AP view has limited sensitivity: 50%Deep sulcus signToo sharp heart border/hemidiaphragm signIncreased lucency over lower chest

Cant see vessels

PNEUMOTHORAX: OpenPNEUMOTHORAX: Open- Gunshot or other wound (hole > 2/3 tracheal diameter) +/-

exit wound

- Air enters the wound rather than trachea and leads to hypoxia.

- Unequal breath sounds

PNEUMOMEDIASTIUMPNEUMOMEDIASTIUMUsually from ruptured alveoli.Can also be from trachea, bronchi,

esophagus, bowel and neck injuries.

Air forms linear / curvilinear lucencies outlining mediastinal contours :Air anterior to pericardium: pneumopericardiumAir around pulmonary artery and main branches: ring around artery signAir outlining major aortic branches: tubular artery signAir outlining bronchial wall: double bronchial wall signContinuous diaphragm sign: due to air trapped posterior to pericardiumV sign of Naclerios: “V” sign at aortic-diaphragm junction

Paediatric pneumomediastinum: may have slightly different appearances:elevated thymus: thymic wing signair crossing the superior mediastinum: haystack sign 

Ring around the artery signRing around the artery sign

V sign of nacleriosV sign of naclerios

PneumopericardiumPneumopericardium

Spinnaker / angel wing signSpinnaker / angel wing sign

Haystack sign Haystack sign air around heart makes it look like a Monet paintingair around heart makes it look like a Monet painting

PNEUMOMEDIASTINUM: CTPNEUMOMEDIASTINUM: CT

Tracheal / bronchial tearsTracheal / bronchial tears

• Most common site - near the carina, because the airway is fixed and subject to shear injury.

• Tears within the mediastinal pleura – pneumomediastinum

• Tears beyond the mediastinal pleura - pneumothorax.

• Left main bronchus : has a longer mediastinal course than the right main bronchus & so injury - more likely to cause a pneumomediastinum & vice versa.

• Severe injuries, both a pneumomediastinum and a pneumothorax may be present.

Fallen Lung signFallen Lung signWith complete laceration of the main bronchus, the bronchus may become partially or completely detached, allowing the lung to fall into a dependent lateral position

PneumoperitoneumPneumoperitoneum

.

PneumoretroperitoneumPneumoretroperitoneum

HEMOTHORAXHEMOTHORAXVenous or arterial bleedingCan miss hundreds of cc’s on supine film

HEMOTHORAXHEMOTHORAX

CT: HEMOTHORAXCT: HEMOTHORAX

35-70 HU

PULMONARY CONTUSION and PULMONARY CONTUSION and LACERATIONLACERATION

Contusion: Blood in intact lung parenchyma. Non-penetrating.

Laceration: Blood in torn lung parenchyma

Can’t tell difference on chest film. Contusions peak in 2-3 days, begin to resolve in a week; lacerations take much longer to resolve and may leave scars

ContusionContusion• Manifest at the time of the initial examination• Little tendency to increase in severity with subsequent

examinations. • Radiographic clearing within 48 hours. • Features are often not localised in a lobar or segmental

pattern.

Plain film Not sensitive. • Faint patchy consolidative following history of blunt trauma. • CT – focal, non segmental parenchymal opacification. • Can have sub-pleural sparing with smaller contusions• Commoner posteriorly and in lower lobes.

LacerationsLacerations• Almost always have concurrent contusion

• PathologyClassification:

Type I - compression rupture: most common type of laceration that usually occurs as a 2-8 cm lesion in the central lung

Type II - compression shear: occurs after sudden compression of the lower chest when the lung suffers from a shear injury to the spine

Type III - direct puncture / rib penetration: occur with a penetrating fractured rib; these lesions are commonly multiple

Type IV - adhesion tears: occurs in sudden injuries of the chest wall where prior pleuropulmonary adhesions had been created

•Pattern can be similar to contusion•Often have added rib fractures & pneumothorax

CT •Regions of pulmonary contusion with added blebs (pneumatoceles) with air fluid levels.

•Due to normal pulmonary elastic recoil, lung tissues surrounding a laceration often pull back from the laceration which manifesting at CT as a round or oval cavity, instead of having the linear appearance in other solid organs.

•Severe laceration have gross disruption of lung parenchymal architecture.

DIAPHRAGM InjuriesDIAPHRAGM Injuries5% of major blunt

trauma, also thoraco-abdominal penetrating trauma

Left clinically injured more than right 60/40

Sensitivity of Chest film 40%. CT better, but still misses some

Hard signs: NGT through g.e. junction then up into chest, and hollow viscus above diaphragm

Soft signs: Indistinct diaphragm, effusion, atelectasis

Position of NG TubePosition of NG Tube

Gut in ChestGut in Chest

Vascular InjuryVascular Injury

Signs of mediastinal haematoma:widened mediastinumindistinct or abnormal aortic contourdeviation of trachea or NGT to the rightdepression of left main bronchuswidened paraspinal stripe

CTCTIndirect signs of aortic injury:mediastinal haematomaperiaortic fat stranding

CTA : sensitivity 100%; specificity 100%.Signs of mediastinal haematoma:abnormal soft tissue density around mediastinal structuresLocation – periaortic haematoma than isolated mediastinal haematoma remote from the aorta.

Signs of aortic injury:intraluminal filling defect (intimal flap or clot)abnormal aortic contour (mural haematoma)Pseudoaneurysm & extravasation of contrast