Diagnostic Imaging of Blunt Chest Trauma

1. Diagnostic Imaging of Blunt Chest Trauma Phil Goebel Oregon Health Sciences University March 2005

2. Special thanks to Drs. Marc Gosselin and Steven Primack for their advice and radiographs.

3. Epidemiology of Blunt Chest Trauma(It’s really quite simple.)

4. #1

5. #2

6. Epidemiology of Blunt Chest Trauma • Motor Vehicle Crashes (63-78%) • Falls (10-17%) • Other • Industrial Accidents • Blast injuries (limited demographic segments)

7. Biomechanics of Blunt Chest Trauma • Degree of Compression predicts severity of chest wall injury. • Visceral Injury is dependent on the Velocity of Deformation not the degree/magnitude of compression. Mayberry JC. Imaging in thoracic trauma: the trauma surgeon's perspective. Journal of Thoracic Imaging. 15(2):76-86, 2000 Apr

8. Biomechanics of Blunt Chest Trauma (continued) • Visceral injury is most often caused by high velocity energy waves disrupting crucial tissue structures and planes while passing through the thoracic cavity, rather than compression of the chest wall directly impinging on those structures.

9. Biomechanics of Injury

10. A- Aorta B- Bronchi C- Cord C- Contusions D- Diaphragm E- Esophagus F- Flail Chest F- Fracture G- Gas H- Heart H- Hemothorax H- Hematoma H- Hemorrhage I- Iatrogenic Approach to Chest Radiology in TraumaBorrowed from The ABC’s of Trauma from Jud Gurney MD, FARC (www.chestx-ray.com)

11. Approach to Chest Radiology in Trauma • Systematically Look for the Injuries to be discussed in the following slides. • AVOID “satisfaction of search” by noting injuries as you come across them and continuing your systematic search to the end. (ie don’t let that amazing flail chest distract you from the barely contained aortic tear.)

12. Aortic Injury • Dismal Survival Rate ~80% die before reaching the ED • In 1958 of nonoperative patients who arrived alive to the hospital- • 30% die within 6 hours • 50% within 24 hours • 72% within 8 days • 90% within 4 months Parmley LF, Mattingly TW, Manion TW, et al: Nonpenetrating traumatic injury of the aorta. Circulation XVII:1086, 1958.

13. A is for Aortic Injury • In a prospective, descriptive study of Traumatic Aortic Injury patients arriving alive to the ED. (n= 274) • 100% mortality in patients in extremis or with free rupture of the aorta prior to surgery. • 50% mortality for patients with other injuries or age preventing surgery • 31% mortality overall • 14% mortality for stable patients (4% directly attributable to aortic injury. Remaining 10% due to other injuries) Fabian TC, Richardson JD, Croce MA, et al. Prospective study of blunt aortic injury: multicenter trial of the American Association for the Surgery of Trauma. Journal of Trauma. 1997; 42: 374–380

14. Aortic Injury • Findings on CXR suggestive of Aortic Injury • “Wide Mediastinum” traditionally >8 cm • Increased opacity of right paratrachial stripe • Loss of distinction of Aortic Arch • Rightward deviation of trachea and NG tube • Downward deviation of Left main bronchus >40-45 degrees • Left apical cap

15. Beware the Wide Mediastinum • Multiple Causes of simple widened mediastinum besides trauma. • Full SVC = adequate fluid resuscitation • Mediastinal Fat • Patient positioning • Magnification due to change in x-ray plate positioning • Look for indirect signs of mediastinal hematoma listed on previous slide. Traumatic aortic injury rarely occurs without mediastinal hematoma.

16. Rightward deviation of trachea Opaque Paratracheal stripe Decreased definition of aortic arch

17. pseudoaneurysm

19. Normal paratracheal stripe Loss of distinction of Aortic Arch Rightward deviation of trachea Caudad displacement of Left Main Bronchus Caudad dispalcement of left main bronchus Rightward deviation of NG tube

20. Intimal Tear Sternal fracture Hematoma

21. Evaluation of Aortic Injury • CXR • Low number of false negatives. Too many false positives using widened mediastinum criterion. • CT Aortography • Should be considered based on mechanism of injury and positive CXR findings. • Reveals other causes of mediastinal hematoma • Faster than angiography with fewer personnel required • Sensitivity 92-100% Specificity 100%* • Can be used as sole diagnostic tool to evaluate for aortic injury.** • Thoracic Angiography • Traditional Gold Standard • Sensitivity and Specificity 90-100% *1. Scaglione M. Pinto A. Pinto F. Romano L. Ragozzino A. Grassi R. Role of contrast-enhanced helical CT in the evaluation of acute thoracic aortic injuries after blunt chest trauma. European Radiology. 11(12):2444-8, 2001. 2. Parker MS. Matheson TL. Rao AV. Sherbourne CD. Jordan KG. Landay MJ. Miller GL. Summa JA. Making the transition: the role of helical CT in the evaluation of potentially acute thoracic aortic injuries. American Journal of Roentgenology. 176(5):1267-72, 2001 **S. W. Downing, J. S. Sperling, S. E. Mirvis, M. G. Cardarelli, T. B. Gilbert, T. M. Scalea, and J. S. McLaughlinExperience with spiral computed tomography as the sole diagnostic method for traumatic aortic ruptureAnnals of Thoracic Surgery, August 1, 2001; 72(2): 495 - 502.

22. How Should I Evaluate the Aorta? • What’s the pretest probability? • For a clinical prediction rule see: http://www.chestx-ray.com/Lectures/ABCTrauma/BluntChestTr.html • If any of the following are present, Helical CT or Aortography is warranted. If none of these factors are present chest x-ray alone may be sufficient. • Patient older than 50 years • Unrestrained • Hypotension (Systolic< 90mm Hg in ED) • Thoracic injury (fractured rib(s), pulmonary contusion/laceration, or pneumothorax) • Abdominopelvic injury (pelvic fx, lumbar fx, or injury requiring laparotomy) • Extremity Fracture (femur, tibia, fibula, humerus, radius, or ulna) • Head injury (skull fracture, hemorrhage, unconscious at evaluation)

23. So you still haven’t answered the question. CT or Angio? • Older data comparing older CT scanners and angiography suggest that aortography is the best diagnostic tool. • However, the literature is shifting towards helical high resolution CT as the modality of choice. • Talk to your radiologist and trauma/cardiothoracic surgeons to determine what the standard and hopefully simultaneously best choice at your hospital is.

24. B is for Bronchial Injury • Lacerations of the Trachea and Bronchi are rare injuries in blunt trauma, and often are missed in the initial trauma evaluation. • Most injuries occur within 2.5 cm of the carina and involve the bronchi more frequently than the trachea.

25. Tracheobronchial Tear • Radiologic Findings that point towards tracheobronchial injury: • Pneumomediastinum, Pneumothorax, Subcutaneous emphysema. • Persistence of pneumothorax after placement of chest tube. • Fallen lung sign= collapse of the lung away from the hilum.

26. Tracheobronchial Tear pneumothorax Atelectatic lung fallen away from the hilum

27. Fallen Lung Sign

28. Bronchus Intermedius Tear pneumomediastinum Chest tube Persistent pneumothorax Presentation 2 day f/u

29. Persistent Pneumothorax Lung falling away from the hilum Chest tube

30. C- is for Cord • 62% of patients with thoracic spinal injuries have neurological symptoms. • 70 % of thoracic spinal fractures will result in signs of mediastinal hematoma on the chest radiograph. If there is concern about spinal injury dedicated plain radiographs of the spine or CT. • The most common types of fractures are anterior wedge fractures and burst fractures near the thoracolumbar junction.

31. Wedge Compression Fracture Anterior wedge fracture

32. Burst Fracture

33. Thoracic Spine Fracture - CT Hematoma Burst Fx Rib Fx with subcutaneous Air and underlying pulmonary contusion

34. C- is for Contusion • Pulmonary Contusion • Focal areas of consolidation representing areas of edema, and parenchymal hemorrhage. • Nonsegmental consolidation usually in the periphery and adjacent to chest wall trauma. • Usually resolves in 2-3 days. • Must be differentiated from aspiration, atelectasis, and pulmonary edema. • Best characterized on CT scan. Zinck SE, Primack SL. Radiographic and CT Findings in Blunt Chest Trauma. Journal of Thoracic Imaging. 15(2) pp 87-96 2000

36. D- is for Diaphragm • Diaphragmatic injuries are rare in blunt chest trauma patients (1-8%) • Usually left sided and posterior-lateral • More easily diagnosed in the absence of positive pressure ventilation. • Radiographic signs include: • Collar sign= pinched stomach or loop of bowel in the chest. • Dependent viscera sign= Any segment of the GI tract in contact with the thoracic wall without intervening diaphragm. (Seen on CT) • Unusual course of the NG tube. Shanmuganathan, K. Imaging of Diaphragmatic Injuries. Journal of Thoracic Imaging. 15(2)  pp 104-111 April 2000

37. Diaphragm Injury - Chest Radiograph Collar Sign

38. Diaphragm Herniation Collar Sign

39. Dependent Viscera Sign

40. Diagnostic Imaging of Blunt Chest Trauma • That covers A-D of the pneumonic. • Remember to avoid satisfaction of search, and be systematic. • Use the most efficient modality to evaluate the severely injured patient. • E-I of the pneumonic will be covered in a future lecture.

41. A- Aorta B- Bronchi C- Cord C- Contusions D- Diaphragm E- Esophagus F- Flail Chest F- Fracture G- Gas H- Heart H- Hemothorax H- Hematoma H- Hemorrhage I- Iatrogenic Approach to Chest Radiology in TraumaBorrowed from The ABC’s of Trauma from Jud Gurney MD, FARC (www.chestx-ray.com)

42. Review Articles/References to read on your own • The ABC’s of Trauma from Jud Gurney MD, FARC (www.chestx-ray.com) • Zinck SE, Primack SL. Radiographic and CT Findings in Blunt Chest Trauma. Journal of Thoracic Imaging. 15(2) pp 87-96 2000 • Mayberry JC. Imaging in Thoracic Trauma: The Trauma Surgeon's Perspective. Journal of Thoracic Imaging; 15(2) pp 76-86 April 2000