Imaging of Thoracic Trauma

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  • 1. www.RiTradiology.com www.RiTradiology.com Imaging of Thoracic Trauma Rathachai Kaewlai, MD Ramathibodi Hospital, Mahidol University, Bangkok Emergency Radiology Minicourse 2013 Slides available at RiTradiology.com or Slideshare.net/rathachai
  • 2. www.RiTradiology.com www.RiTradiology.com Introduction •  Trauma leading cause of death in developing countries | 4th in first-world countries •  Loss of productive years of life – because most occur in young individuals •  Traffic accidents, falls, recreational, violence •  Rapid diagnosis important to avoid morbidity and mortality
  • 3. www.RiTradiology.com www.RiTradiology.com Introduction •  Thoracic injuries –  10-15% of all trauma –  25% of trauma fatalities •  Blunt (70-80%) > penetrating –  Compression  thoracic wall injuries –  High velocity injury  visceral injuries •  Rx mostly conservative. Thoracotomy rate... –  <10% in blunt thoracic trauma –  15-30% in penetrating thoracic trauma Image from http://www.veomed.com/va041842172010
  • 4. www.RiTradiology.com www.RiTradiology.com Initial Assessment •  Primary survey – Airway (prevent hypoxia, stridor = UAO) – Breathing (tension ptx, open ptx, flail chest) – Circulation (BP, pulse monitor, arrhythmia, massive hemothorax, cardiac tamponade) •  Secondary survey – Others Mainlyfromphysicalexam
  • 5. www.RiTradiology.com www.RiTradiology.com Imaging Survey •  Portable CXR – Tube/line malposition – Large pneumothorax, hemothorax – Flail chest – Mediastinal widening (suspected aortic injury) •  Ultrasound (as a part of extended FAST) – Pericardial effusion (presumed hemopericardium) – Pneumothorax / hemothorax
  • 6. www.RiTradiology.com www.RiTradiology.com Portable Trauma CXR •  Tube and line malposition – most critical •  Large pneumothorax •  Large hemothorax •  Flail chest •  Mediastinal widening •  Other important things: pneumomediastinum, diaphragm injury, unstable spine fractures
  • 7. www.RiTradiology.com www.RiTradiology.com Tube/line Malposition Right mainstem bronchial intubation
  • 8. www.RiTradiology.com www.RiTradiology.com Tube/line Malposition Left chest tube – chest wall placement
  • 9. www.RiTradiology.com www.RiTradiology.com Pneumothorax on Supine CXR •  Deep sulcus •  Hyperexpanded hemithorax •  Increased lucency •  Increased sharpness of heart border •  Subcutaneous emphysema
  • 10. www.RiTradiology.com www.RiTradiology.com Pneumothorax on Supine CXR 12 hours later
  • 11. www.RiTradiology.com www.RiTradiology.com Tension Pneumothorax •  One-way valve •  Mediastinum displaced to other side – Decreasing venous return – Compressing opposite lung •  Clinical diagnosis! (air hunger, respiratory distress, tachycardia, hypotension, tracheal deviation, JVD, etc) •  Immediate decompression needed Image from freedictionary.com
  • 12. www.RiTradiology.com www.RiTradiology.com Tension Pneumothorax •  Hyperexpanded chest •  Shift of mediastinum •  Depression of hemidiaphragm •  Sometimes we can see it on imaging –  Can be insidious, esp in mechanical ventilation Postmortem CXR. Image from trauma.org
  • 13. www.RiTradiology.com www.RiTradiology.com Flail Chest •  Most significant chest wall injuries •  Paradoxical movement of a segment of chest wall •  Problems of underlying lung contusion and pain leading to hypoxia •  3 or more contiguous segmental rib fractures •  Variations include anterior flail, posterior flail and flail including sternum •  CXR may not show all fractures, esp anterior and lateral fractures Images from wikipedia
  • 14. www.RiTradiology.com www.RiTradiology.com Flail Chest Anterior rib fractures difficult to see on CXR Pneumothorax doesn’t clear even after chest tube placement. 3D CT shows displaced right rib fractures (note absent rib attachment to the sternum (green arrows).
  • 15. www.RiTradiology.com www.RiTradiology.com Hemothorax •  Blood in pleural space •  Source: chest wall, lung parenchyma, heart or great vessels •  Chest wall injuries can cause bleeding from intercostal and IMA •  As much as 1,000 mL of blood may be missed when viewing portable supine CXR (400-500 mL required for blunt CP angle on upright CXR) •  Massive hemothorax –  >1,500 mL of blood or –  > 1/3 of blood volume Supine CXR: apical capping, lateral extrapleural density
  • 16. www.RiTradiology.com www.RiTradiology.com Trauma Ultrasound: FAST •  FAST includes pericardial and pleural spaces evaluation •  Fluid in acute trauma = blood until proven otherwise •  Straightforward, “Yes/No” answer •  Pericardial evaluation is very important and should be the first part of all FAST scans, esp. penetrating trauma
  • 17. www.RiTradiology.com www.RiTradiology.com Pericardial Evaluation •  Presence of pericardial fluid •  Source of blood –  Great vessels –  Heart –  Pericardial vessels •  Tamponade physiology? –  Collapsed right heart chambers: right atrium – sensitive, right ventricle - specific –  Distended IVC (caval index = 1) •  Key elements of tamponade –  Rate of fluid accumulation –  Effectiveness of compensatory mechanisms Nypemergency.org
  • 18. www.RiTradiology.com www.RiTradiology.com Pleural Evaluation •  Perihepatic and perisplenic views of FAST must include “pleural cavity”
  • 19. www.RiTradiology.com www.RiTradiology.com Pleural Evaluation Extended FAST (EFAST) •  Best resolution of pleural interface with high- resolution probe and small footprint •  But most practical using same probe as FAST
  • 20. www.RiTradiology.com www.RiTradiology.com Detection of Pneumothorax •  Pneumothorax occult on CXR in 29-72% •  EFAST can identify pneumothorax before CXR •  Identify contiguity of visceral and parietal pleura using simple US signs –  To exclude pneumothorax –  Extended FAST (EFAST) –  Normal = lung sliding (B), seashore sign (M mode) –  Abnormal = loss of lung sliding (B), stratosphere (M), lung point (B & M)
  • 21. www.RiTradiology.com www.RiTradiology.com Detection of Pneumothorax: Principles •  “Air rises, water descends” – Dependent disorders: effusion, consolidation – Nondependent disorders: pneumothorax, interstitial process
  • 22. www.RiTradiology.com www.RiTradiology.com Normal Appearance: Evaluate for Pneumothorax - EFAST •  Sagittal view at mid- clavicular line “bat- sign” – Lung sliding? – A-line sign? – Lung point?
  • 23. www.RiTradiology.com www.RiTradiology.com Detection of Pneumothorax •  Normal lung sliding –  Twinkling at level of pleural line in real time –  Sliding of visceral against parietal pleura –  Relative motionless of chest wall to lungs –  Seashore appearance on M-mode
  • 24. www.RiTradiology.com www.RiTradiology.com Pneumothorax: Loss of Lung Sliding •  Sensitivity 80-100% (lower in trauma) •  Specificity 83-100% •  Real-time US •  M mode = Barcode or stratosphere sign Barcode sign
  • 25. www.RiTradiology.com www.RiTradiology.com Pneumothorax: A line sign •  Seeing A-line with loss of lung sliding  suspect pneumothorax •  One B-line can R/O pneumothorax where probe is applied Lung point •  Most specific sign •  At border between aerated lung and ptx, there is intermittent appearance of lung sliding during inspiration/ expiration
  • 26. www.RiTradiology.com www.RiTradiology.com Looking for Pneumothorax on US Lung sliding? Yes Pneumothorax ruled out No B- lines? Yes No Lung Point? No Use other tools Yes Pneumothorax Adapted from Lichtenstein D.
  • 27. www.RiTradiology.com www.RiTradiology.com Detection of Pneumothorax •  Absent lung sliding – Sensitivity 100%, specificity 78% •  Absent lung sliding + A line sign – Sensitivity 95%, specificity 94% •  Lung point – Specificity 100% •  EFAST more sensitive than portable CXR trauma Lichtenstein DA et al. Crit Care Med 2005
  • 28. www.RiTradiology.com www.RiTradiology.com Pitfalls of US on Pneumothorax •  “Loss of lung sliding” alone is not specific for pneumothorax – Pleural adhesion/thickening – Atelectasis – Lobec/pneumonectomy – One-lung intubation •  Look for “Lung Point” •  Comparison with contralateral lung
  • 29. www.RiTradiology.com www.RiTradiology.com CT in Thoracic Trauma •  Role of CT used to be for R/O thoracic aortic injury •  Now CT believed to be most accurate for diagnosis several thoracic trauma •  Yield of CT is higher when done after an abnormal initial CXR or performed selectively based on clinical criteria
  • 30. www.RiTradiology.com www.RiTradiology.com Patient Preparation for CT •  Hemodynamic – must be stable •  NPO – should not wait •  IV contrast – a must (if conditions allow) •  Renal function test – risk/benefit ratio •  Pregnancy test - yes
  • 31. www.RiTradiology.com www.RiTradiology.com CT Technique •  Helical mode •  Thinnest collimation possible and reformatted to 2-2.5 mm for viewing •  120 kV •  Automatic tube current modulation •  No plain scan •  Late arterial phase + delays at site of vascular injuries •  Routine coronal and sagittal reformations
  • 32. www.RiTradiology.com www.RiTradiology.com What Else We Are Looking For? •  ABC’s of Jud W. Gurney (chestx-ray.com) – Systematic evaluation of blunt thoracic trauma – A, B, C, D, E, F, G, H, I •  Missed diagnosis – 4% died within 24 hours – 30% missed interpreted •  Aortic injury •  Diaphragmatic trauma •  Flail chest
  • 33. www.RiTradiology.com www.RiTradiology.com ABC’s Approach* Aortic injury Bronchial injury Cord injury Diaphragm injury Esophageal tear Flail chest Gas (pneumothorax) Heart (cardiac injury) Iatrogenic tube/line malposition *Borrowed from Jud W. Gurney MD FACR
  • 34. www.RiTradiology.com www.RiTradiology.com Cautions •  Satisfaction of search •  Subtle signs •  CXR is a “screening” exam. Rarely it is diagnostic of an injury
  • 35. www.RiTradiology.com www.RiTradiology.com Aortic Injury (TAI) •  16% MVA fatalities •  85-90% mortality prior to reaching hospital – Survivors •  30% died within 6 hours •  50% died within 24 hours •  72% died within 8 days •  90% died within 4 months uvahealth.com
  • 36. www.RiTradiology.com www.RiTradiology.com Azizzadeh A et al. J Vasc Surg 2009
  • 37. www.RiTradiology.com www.RiTradiology.com Aortic Injury (TAI) CXR Signs of TAI Mediastinal widening (>8 cm at aortic arch level, or by visual assessment) Loss of AP window, descending T-aorta Tracheal shift to the right of T4 SP NG tube displacement to the right Widened paraspinal or right paratracheal stripes Left apical pleural cap sign Normal (10-15%) For CXR: PPV 10%, NPV 98% but TAI is life-threatening, keep low threshold for CT X-ray signs are related to mediastinal hematoma >8 cm
  • 38. www.RiTradiology.com www.RiTradiology.com Most common location = aortic isthmus (90%) Pseudoaneurysm and periaortic hematoma
  • 39. www.RiTradiology.com www.RiTradiology.com Aortic Injury (TAI) •  Indirect CT signs –  Periaortic hematoma •  Direct CT signs –  Pseudoaneurysm –  Intimal flap –  Intimal irregularity –  Pseudocoarctation –  Extravasation •  Term “traumatic dissection” is discouraged (confusing with aortic dissection related to hypertension) Pseudoaneurysm and periaortic hematoma
  • 40. www.RiTradiology.com www.RiTradiology.com Aortic Injury (TAI) •  Periaortic mediastinal hematoma –  Small veins in area of injury or vasa vasorum –  Does not arise directly from aorta tear –  Usually adjacent to aoric arch and prox descending aorta, but may tracts down descending aorta to diaphragm (retrocrural) Retrocrural hematoma seen on abdominal CT without clear etiology (ie, spine fracture) should raise a concern for TAI
  • 41. www.RiTradiology.com www.RiTradiology.com Aortic Injury (TAI) •  Transesophageal echocardiography (TEE) –  Heart (for contusion) and t-aorta –  More invasive than CT and usu requires sedation –  Blind spots: arch, arch vessels, distal ascending aorta –  May be used intraoperatively •  Catheter aortography –  Prior gold standard, now reserved for selected cases and for endovascular Rx
  • 42. www.RiTradiology.com www.RiTradiology.com (Tracheo)Bronchial Injury •  1.5% of major thoracic trauma •  30% missed •  80% within 2.5 cm of carina J R Coll Surg Edin 1999 Persistent or Progressive Pneumothorax or Pneumomediastinum
  • 43. www.RiTradiology.com www.RiTradiology.com (Tracheo)Bronchial Injury •  Traumatic pneumomediastinum: must exclude –  Airways injuries (larynx, tracheobronchus) –  Esophageal injuries •  Bronchoscopy gold standard •  However, most are benign –  Extension of pneumothorax through pleural tear –  Pulmonary alveolar rupture “Macklin effect”
  • 44. www.RiTradiology.com www.RiTradiology.com Cord Injury •  25% spine fractures •  90% neurologic injury •  Most common site = T9-11 –  Critical zone –  Transition of facet joint orientation: T facets face inward, L facets face outward •  Difficult assessment on trauma CXR –  Portable technique –  Rule of 2’s Thoracic spine fractures often causes spinal cord injury because cord is large in relation to the canal Image from superhuman.net.au
  • 45. www.RiTradiology.com www.RiTradiology.com •  On AP view, look at pedicles and spinous processes •  Everything no more than 2 mm from one level to the next –  Interspinous space –  Interpedicular distance •  Elevated paravertebral stripes –  Also sign of TAI
  • 46. www.RiTradiology.com www.RiTradiology.com Injuries with paraspinal hematoma in upper T can simulate mediastinal widening (findings of TAI)
  • 47. www.RiTradiology.com www.RiTradiology.com Diaphragmatic Trauma •  5% blunt thoracic trauma •  Left > right •  70% initially missed
  • 48. www.RiTradiology.com www.RiTradiology.com Diaphragmatic Trauma CXR Signs Diaphragmatic elevation Abdominal organ in thorax NG tube in thorax Basilar lung opacities/ hemothorax Mediastinal shift Distorted diaphragm contour Lower rib fracures
  • 49. www.RiTradiology.com www.RiTradiology.com Diaphragmatic Trauma CT Signs Direct discontinuity (“tear”) of diaphragm Herniation of abdominal contents above diaphragm Collar sign Dependent viscera sign Collar sign
  • 50. www.RiTradiology.com www.RiTradiology.com Esophageal Perforation •  Very rare injury •  Upper esophagus most common location Suspect this injury when pneumomediastinum is present in a trauma patient --- Next step is CT or water-soluble contrast esophagogram
  • 51. www.RiTradiology.com www.RiTradiology.com Flail Chest Rib fractures •  Most common findings after blunt chest trauma •  CXR sensitivity 18-50% •  Most common = rib 4-9 –  Rib 1-3  neurovascular injury –  Rib 9-12  liver, spleen, kidney •  Absence of fracture lines: –  In adults >65 years may warrant rib series. –  In children, it does not mean mild injuries because of pliable ribs
  • 52. www.RiTradiology.com www.RiTradiology.com Flail Chest •  > 3 consecutive segmental rib fractures •  Anterior, posterior or costosternal segments •  Paradoxical motion of chest wall  respiratory compromise
  • 53. www.RiTradiology.com www.RiTradiology.com Gas (Pneumothorax) •  15-40% of cases CXR Signs on Supine View Deep sulcus Sharp cardiac borders Basilar hyperlucency Visualized pericardial fat tags Deep sulcus sign
  • 54. www.RiTradiology.com www.RiTradiology.com Heart Injury •  Mostly myocardial contusion •  Less common – Pericardial laceration – Rupture of myocardium – Rupture of valve – Laceration of coronary artery
  • 55. www.RiTradiology.com www.RiTradiology.com Heart Injury •  Hemopericardium •  Pneumopericardium •  Pericardial laceration
  • 56. www.RiTradiology.com www.RiTradiology.com Conclusions •  Portable CXR: Tube/line position, hemo- pneumothorax, flail chest, mediastinal widening •  US: hemothorax, pneumothorax •  CT: aortic injury, diaprhagm and tracheobronmchial injury •  Use CT with a lower threshold especially if initial CXR is abnormal –  IV contrast needed –  Coronal and sagittal reformats needed