Imaging of Thoracic Trauma: Tips and Traps Arun C. Nachiappan, MD Associate Professor of Clinical Radiology University of Pennsylvania
None Disclosures
Objectives Describe blunt and penetrating traumatic injuries to the chest Discuss iatrogenic injuries to the chest Identify Grade V and Grade VI (AASTclassification) thoracic injuries
Outline AAST Grading Scale of thoracic trauma Lung and Airways Pulmonary Tracheobronchial Pleura Mediastinum Esophageal Cardiac Aortic Diaphragm Chest wall Thoracic Spine
AAST Grade American Association for the Surgery of Trauma Grades I to VI Grade I Least severe injury Grade V Most severe SURVIVABLE injury Grade VI Non-survivable Following AAST tables accessed from http://www.aast.org/library/traumatools/injuryscoringscales.aspx
Pulmonary contusion and laceration
Pulmonary contusion and laceration Contusion Laceration
Pulmonary Parenchymal Injury Contusion: Focal areas of edema and hemorrhage in the alveoli, but no tear Groundglass opacity or consolidation Appears immediately; starts to resolve in 1-2 days; completely clears in 3-10 days
Pulmonary Parenchymal Injury Laceration: Linear tear in lung parenchyma Hematoma or Pneumatocele Lung Herniation Into chest wall via a defect
Atelectasis Enhancing lung parenchyma
Tracheobronchial Injury CT Airway Protocol 1 mm thick axial slices Scout landmarks Skull base to a level 4cm below the carina Oblique coronal and sagittal series can help optimize visualization of airways 3D reconstructions Virtual bronchoscopy, volume rendering
Tracheal laceration Kaewlai, et al. Radiographics 2008;28:1555 1570
Tracheobronchial Injury Mechanism Trauma Location of tear Trachea pneumomediastinum Right main stem bronchus pneumothorax Left main stem bronchus pneumomediastinum Mainstem bronchus Fallen lung sign Morbidity and Mortality occurs in 3% of fatal trauma 30-80% die prior to arrival at ED
www.eurorad.org Fallen lung sign
Tracheobronchial Injury Mechanism Iatrogenic Rigid bronchoscopy Tracheostomy tube Cuff overinflation Stylet injuring the posterior membrane
Pneumothorax Hemothorax Pleural injury
Pneumothorax Hemothorax
Esophagus Cardiac Aorta Mediastinal injury
Pneumomediastinum 64yo F PMH scleroderma, recent esophageal manometry/ph probe
Pneumomediastinum Trap: Subtle pneumomediastinum can be mistaken for a pneumothorax Thicker line (mediastinal + visceral pleura) Associated with extrapleural air Associated with subcutaneous air Conservative management If severe, may need to adjust vent settings
95 y/o F status post endoscopy Extensive subcutaneous emphysema and pneumomediastinum
Pneumomediastinum Source of pneumomediastinum Pleural space PTX ruptures into mediastinum From the subcutaneous tissues of the chest wall, neck Via thoracic inlet Pulmonary Ruptured bleb Barotrauma Mediastinum Esophageal, Tracheobronchial injury
Esophageal Injury Esophagram in same patient 5-10 mm perforation at the posterior pharyngoesophageal junction, with contrast dissecting into posterior mediastinum
Tip Paravertebral density (hematoma) is a clue to look for thoracic vertebral body fracture
Cardiac injury Cause of death in 25% of fatal trauma Blunt (MVA) or Penetrating (GSW and stab wound) Pericardium Hemopericardium, Pneumopericardium Cardiac Chamber Rupture Anterior surface of the heart, Right ventricle Mortality rate 76%
Hemopericardium New placement of cardiac device with lead perforating heart
Pericardium Tip Measure density of pericardial effusion to evaluate for hemopericardium Risk of cardiac tamponade Fluid may need to be drained
Valvular injury Cardiac injury Aortic valve most commonly injured Minimal damage, laceration, or detachment Mitral and tricuspid valve injury due to ruptured papillary muscle Coronary artery injury rare LAD most commonly involved, resulting in acute MI
Thoracic Aortic Injury Mediastinal hematoma
Thoracic Aortic Injury Irregularity of aortic contour Mediastinal hematoma
Thoracic Aortic Injury Mediastinal hematoma
Thoracic Aortic Injury Mediastinal hematoma
? Left Subclavian Artery compromise
? Left Subclavian Artery compromise
Question The most common location for acute traumatic aortic injury is: A. Aortic isthmus B. Ascending aorta near the aortic root C. Distal descending aorta near at the diaphragmatic hiatus D. Diverticulum of Kommerell E. Mid descending thoracic aorta at the level of takeoff of intercostal arteries.
Question The most common location for acute traumatic aortic injury is: A. (#1) Aortic isthmus B. (#2) Ascending aorta near the aortic root C. (#3) Distal descending aorta near at the diaphragmatic hiatus D. (x) Diverticulum of Kommerell E. (x) Mid descending thoracic aorta at the level of takeoff of intercostal arteries.
Traumatic Aortic Injury Mechanism Shearing forces due to rapid deceleration Injury occurs at the fixed points of the thoracic aorta Location Aortic isthmus 90% (fixed point: ligamentum arteriosum) Ascending aorta 8% (fixed point: aortic root) Distal descending aorta 2% (fixed point: diaphragm)
Traumatic Aortic Injury Morbidity and Mortality Cause of death in 20% of fatal high-speed MVA. Up to 90% are dead on arrival 50% mortality if patient is untreated within first 24 hours
Trap Traumatic Aortic Injury Mimics Ductus Diverticulum at the Isthmus Pulsation artifact at the Aortic root
Mediastinal hematoma Look closely for a possible traumatic aortic injury Trap: RUL atelectasis should not be mistaken for Right upper mediastinal hematoma Tip: RUL atelectasis has a partially concave margin, while mediastinal hematoma has a convex margin Tip: The border between the atelectatic right upper lobe and the rest of the right lung will extend from the periphery of the lung to the right hilum
Diaphragm injury Traumatic rupture Abdominal contents in Thorax Tip NG/OG tube tip ends in the thorax
Patient was stabbed. Is there diaphragmatic injury? NG/OG looks appropriate. But, still concern for Left hemidiaphragm injury. Need to get a CT.
GSW in a different patient
GSW Bullet fragment
Spleen not visualized in LUQ abdomen Small nodularity in Left pleural space near L hemidiaphragm
Thoracic splenosis due to prior diaphragm injury Can confirm with NM sulfur colloid test
Diaphragm injury
Chest wall/ Spine injury Rib fracture (s) Flail chest Sternal fracture Shoulder or clavicle fracture/dislocation
5 mm axial slice: difficult to see left 1 st rib fracture
1mm thick axial slice in bone algorithm: easier to see Left 1 st rib fracture
Thoracic Spine injury Concern for spinal canal injury Order MR thoracic spine
Take home points Search for causes of pneumothorax or pneumomediastinum to identify additional traumatic findings Specifically search for aortic and cardiac injury Be familiar with the AAST grading system