Imaging of Thoracic Trauma: Tips and Traps. Arun C. Nachiappan, MD Associate Professor of Clinical Radiology University of Pennsylvania

Transcription

1 Imaging of Thoracic Trauma: Tips and Traps Arun C. Nachiappan, MD Associate Professor of Clinical Radiology University of Pennsylvania

2 None Disclosures

3 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

4 Outline AAST Grading Scale of thoracic trauma Lung and Airways Pulmonary Tracheobronchial Pleura Mediastinum Esophageal Cardiac Aortic Diaphragm Chest wall Thoracic Spine

5 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

6 Pulmonary contusion and laceration

7 Pulmonary contusion and laceration Contusion Laceration

8 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

9 Pulmonary Parenchymal Injury Laceration: Linear tear in lung parenchyma Hematoma or Pneumatocele Lung Herniation Into chest wall via a defect

10 Atelectasis Enhancing lung parenchyma

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12 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

13 Tracheal laceration Kaewlai, et al. Radiographics 2008;28:

14 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

15 Fallen lung sign

16 Tracheobronchial Injury Mechanism Iatrogenic Rigid bronchoscopy Tracheostomy tube Cuff overinflation Stylet injuring the posterior membrane

17 Pneumothorax Hemothorax Pleural injury

18 Pneumothorax Hemothorax

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20 Esophagus Cardiac Aorta Mediastinal injury

21 Pneumomediastinum 64yo F PMH scleroderma, recent esophageal manometry/ph probe

22 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

23 95 y/o F status post endoscopy Extensive subcutaneous emphysema and pneumomediastinum

24 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

25 Esophageal Injury Esophagram in same patient 5-10 mm perforation at the posterior pharyngoesophageal junction, with contrast dissecting into posterior mediastinum

26 Tip Paravertebral density (hematoma) is a clue to look for thoracic vertebral body fracture

27 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%

28 Hemopericardium New placement of cardiac device with lead perforating heart

29 Pericardium Tip Measure density of pericardial effusion to evaluate for hemopericardium Risk of cardiac tamponade Fluid may need to be drained

30 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

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32 Thoracic Aortic Injury Mediastinal hematoma

33 Thoracic Aortic Injury Irregularity of aortic contour Mediastinal hematoma

34 Thoracic Aortic Injury Mediastinal hematoma

35 Thoracic Aortic Injury Mediastinal hematoma

36 ? Left Subclavian Artery compromise

37 ? Left Subclavian Artery compromise

38 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.

39 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.

40 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)

41 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

42 Trap Traumatic Aortic Injury Mimics Ductus Diverticulum at the Isthmus Pulsation artifact at the Aortic root

43 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

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45 Diaphragm injury Traumatic rupture Abdominal contents in Thorax Tip NG/OG tube tip ends in the thorax

46 Patient was stabbed. Is there diaphragmatic injury? NG/OG looks appropriate. But, still concern for Left hemidiaphragm injury. Need to get a CT.

47 GSW in a different patient

48 GSW Bullet fragment

49 Spleen not visualized in LUQ abdomen Small nodularity in Left pleural space near L hemidiaphragm

50 Thoracic splenosis due to prior diaphragm injury Can confirm with NM sulfur colloid test

51 Diaphragm injury

52 Chest wall/ Spine injury Rib fracture (s) Flail chest Sternal fracture Shoulder or clavicle fracture/dislocation

53 5 mm axial slice: difficult to see left 1 st rib fracture

54 1mm thick axial slice in bone algorithm: easier to see Left 1 st rib fracture

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56 Thoracic Spine injury Concern for spinal canal injury Order MR thoracic spine

57 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