Advances in MDCT of Thoracic Trauma

Transcription

1 Baltic Congress of Radiology, Riga 2010 Advances in MDCT of Thoracic Trauma Robert A. Novelline, MD Professor of Radiology, Harvard Medical School Director of Emergency Radiology, Massachusetts General Hospital

2 Instructional Objectives: 1. Describe MDCT Protocol for Chest Trauma 2. Review MDCT findings with important injuries of: 1. Pleural spaces 2. Lungs 3. Thoracic Aorta 4. Heart 5. Extra-Aortic Thoracic Arteries 6. Airways 7. Thoracic skeleton Disclosure Statement: I have no relevant financial relationships to disclose

3 Chest Trauma: MDCT Protocol Contrast Material: cc of 370mg concentration IV contrast at 2.5 to 3.0cc/sec Scan at 30 sec delay Scanning Techniques: 4 Slice Detector configuration of 4X1.25mm, view at 2.5/5mm slices 16 Slice Detector configuration of 16x1.25mm, view at 2.5/5mm slices 64 Slice Acquired at 0.625mm, view at 2.5/5mm slices Routine coronal and sagittal reformations Optional volumetric, MIP or CTA reformations 3D workstation available 24/7 May be performed as total body trauma scan

4 1. Injuries of the Pleural Space Hemothorax Occult pneumothorax Tension pneumothorax Pneumothorax size

5 Hemothorax? Active Bleed? Always Measure HU of Pleural Fluid Effusion 7 HU Hemothorax 44 HU with Blood Clots Hemothorax 46 HU With Active Bleed

6 Occult Pneumothorax Definition: Seen at CT but not on chest film >50% pneumothoracies occult In supine patient, air accumulates anteriorly Signs of pneumothorax in supine patient: Increased lucency lower chest Better definition of mediastinum Deep lateral sulcus sign

7 Bilateral Occult Pneumothoraces Increased lucency lower chest Better definition of mediastinum Deep lateral sulcus sign

8 Radiological Signs of Tension Pneumothorax Large pneumothorax with hyperexpansion of ipsilateral chest Splaying ipsilateral ribs Mediastinal shift to opposite side Flattening/inversion ipsilateral hemidiaphragm; deep sulcus sign Before Chest Tube After Chest Tube

9 Do not Overlook Tension Pneumothorax at CT Check scout view and coronal reformats

10 Measuring Pneumothorax Size How Big are They? Right PNX is 496cc; Left PNX is 53.5cc

11 2. Injuries of the lung Lung Contusion Lung Laceration Lung Herniation

12 Pulmonary Contusion Most common lung injury with blunt trauma Hemorrhage and edema in air spaces and interstitium without parenchymal disruption Coup and contra-coup locations Outlines injury track with penetrating trauma

13 Pulmonary Contusion May be solitary or multiple opacities

14 Differentiate Pulmonary Contusion & Aspiration Contusion Contusion Non-segmental, patchy, ill-defined parenchymal opacities Aspiration usually segmental! Thin margin of sparing at pleural surfaces 85% seen in 6 hours; 100% in hours If appearing after 24 hours, not contusion Starts clearing 2-4 days; resolves 10 days Aspiration

15 Pulmonary Contusion with Overlying Right Rib Fracture (Coup Injury)

16 Pulmonary Lacerations Tears of pulmonary parenchyma Due to elastic recoil of lung, tears appear ovoid at CT Caused by blunt forces, or penetrating injuries (stabs, gunshots, rib fractures) Lacerations may be: Air-filled (traumatic pneumatocele) Blood-filled (traumatic hematocele) Both air/blood (traumatic hematopneumocele) Usually accompanied by surrounding contusion Contusion can hide lacerations on radiographs

17 Pulmonary Lacerations

18 Types of Lung Lacerations Blunt Trauma: 1. Compression rupture Laceration within lung parenchyma from chest wall compression causing lung rupture 2. Compression shear Laceration paravertebral location due to shear injury from sudden shifting of lower lobe across the spine 3. Rib penetration tear Small peripheral laceration where a fractured rib has punctured lung 4. Adhesion tear Laceration at lung periphery due to pre-existing adhesion limiting shifting of lung with trauma

19 Types of Lung Lacerations: Penetrating Trauma: 1. Stab Wound Tract of knife or other penetrating object through lung 2. Gunshot Wound Tract of bullet through lung

20 Pulmonary Laceration 1. Compression Rupture (Small)

21 Pulmonary Laceration 1. Compression Rupture (Large)

22 Pulmonary Laceration 2. Compression Shear (Small) Initial Scan Vs 7 Days Later Note Paravertebral Location At 7 Days Laceration Looks Like a Pulmonary Nodule

23 Pulmonary Laceration 2. Compression Shear (Large)

24 Pulmonary Laceration 3. Rib Penetration Tear

25 Pulmonary Laceration Stab Wound to Left Posterior Chest

26 Gunshot Wound to Right Chest Contusion outlines bullet track

27 Lung Herniation Protrusion of pulmonary tissue beyond confines of thoracic cage Traumatic form occurs with rib and costochondral fractures Herniated lung may undergo incarceration and strangulation Beware positive pressure ventilation with herniation

28 3. Injuries of the Thoracic Aortic 8000 cases per year in USA Accounts for 15-20% of all MVC fatalities 90% die before reaching hospital Most involve junction of posterior aortic arch and descending aorta Proposed mechanism is rapid deceleration *99.8% accuracy with 64-slice scanner *Steenburg SD, Ravenel JG, Acute traumatic aortic injury: Experience with 64-MDCT, AJR 2008;191:

29 Thoracic Aorta Trauma Radiographic Findings Mediastinal widening Loss of normal aortic arch Enlarged, irregular aortic arch Left apical pleural cap Displacement NG tube and tracheal air shadow to right Loss of descending aortic line

30 Thoracic Aortic Trauma: Coned-down chest film, CT scout view Left apical pleural cap Displacement of trachea and nasogastric tube to the right

31 Thoracic Aortic Trauma CT Findings Indirect Sign Mediastinal hemorrhage Para-aortic hematoma associated with aortic trauma Direct Signs Intimal tear, flap, disruption False aneurysm formation Aortic contour abnormality Thrombus protruding into the lumen Pseudocoarctation Extravasation of IV contrast

32 Initial Portable Chest, Aortic Trauma Another Patient: Less Impressive Mediastinal Widening

33 CT: Intimal Disruption & False Aneurysm

34 Volume Rendered Aortic Arch; Patient Treated with Aortic Stent Provide Volumetric Reformations 24/7

35 Aortic Injury Multiple Trauma

36 Volumetric Images Aortic Trauma

37 4. Injuries of the Heart Occurs with anterior chest trauma (Often an unrestrained driver who struck the steering wheel) CT may show evidence of cardiac contusion, cardiac laceration, pericardial laceration CT findings include hemopericardium, pneumopericardium, extravasation contrast material, pericardial defect

38 Right Ventricular Laceration with Active Bleed Courtesy of J. Klein

39 Pericardial Laceration with Pneumopericardium

40 5. Extra-Aortic Vascular Injuries Brachiocephalic arteries and branches Internal mammary arteries Intercostal arteries Any of the above may show intimal disruption, false aneurysm, traumatic occlusion or active bleeding Post-process the positive cases

41 Subclavian Artery Traumatic Occlusion

42 Subclavian Artery Injury Without Occlusion Better Detail on MIP Volumetric Axial Scan MIP

43 Internal Mammary Artery Bleed Post-Embolization

44 6. Airway Injuries: Tracheal Laceration: Tracheal lacerations usually longitudinal and posterior at junction of cartilagenous and membranous trachea See secondary signs of subcutaneous and mediastinal emphysema

45 Cervical Tracheal Laceration 2 ½ year trauma victim intubated in the field

46 Tracheal Laceration: CT

47 Adult with Tracheal Laceration Suffered in MVC From T. Eglin

48 6. Airway Injuries (Continued) Bronchial laceration or fracture Often single transverse laceration within 2cm carina Right main stem bronchus more common than left Often associated with a large pneumothorax, pneumomediastinum, and/or subcutaneous air Pneumothorax fails to resolve with chest tube Bronchial stenosis and occlusion may occur later

49 Right Bronchus Laceration

50 Right Bronchus Laceration

51 One Year Later

52 15 year old with Blunt Chest Trauma; 3 Days Later, Left Lung Collapse from Traumatic Left Bronchus Obstruction

53 Volumetric Airway-Lung Reformation

54 7. Injuries of the Thoracic Skeleton Displaced Rib Fractures Flail Chest Posterior Sternoclavicular dislocation Sternal Fracture Thoracic Spine Fracture

55 Displaced Rib Fractures with Chest Deformity

56 Matrix Rib Fixation Plates Rib Fracture Repair

57 Flail Chest 3 or more sequential ribs fractured in 2 or more places Fractured segment moves paradoxically with respiration Normal respiratory motion inhibited; ventilation impaired 3-6% mortality

58 Flail Chest: 73 year old man with chest pain and difficulty breathing after MVC

59 Right Flail Chest: CT Bone Window

60 Bilateral Flail Chest

61 Posterior Sternoclavicular Dislocation

62 Sternal Fracture

63 Do Not Miss Signs of T-Spine Fracture on Portable Chest Radiograph Look for paraspinal hematoma on all trauma chest radiographs

64 T7 Fracture with Paraspinal Hematoma

65 Summary Recommendations MDCT of Thoracic Trauma 1. Perform thoracic trauma MDCT scans with IV contrast material at optimum arterial opacification 2. Routine coronal and sagittal reformations 3. Volumetric/CTA reformations when indicated

66 Thank You! Robert A. Novelline, MD Professor of Radiology, Harvard Medical School Director of Emergency Radiology, Massachusetts General Hospital