ChestChest Trauma

Mohamed Zaitoun

Assistant Lecturer-Diagnostic Radiology Department , Zagazig University Hospitals

EgyptFINR (Fellowship of Interventional

Neuroradiology)-Switzerlandzaitoun82@gmail.com

Knowing as much as possible about your enemy precedes successful battle

and learning about the disease process precedes successful management

Chest Trauma

1-Soft Tissues2-Ribs3-Sternum4-Clavicles & Scapulae5-Spine6-Pleura7-Lung8-Trachea & Bronchi9-Diaphragm10-Mediastinum

1-Soft Tissues :a) Foreign bodies b) Surgical emphysema

2-Ribs :a) Simple fracture b) Flail chest

3-Sternum :a) Fractureb) Sternoclavicular dislocation

4-Clavicles & Scapulae :-Fracture

5-Spine :a) Fracture :-Multiple in 10%-Thoracic spine injuries have a much higher

incidence of neurological deficit than cervical or lumbar spine injuries

b) Cord traumac) Nerve root trauma :-Especially to the brachial plexus

6-Pleura :a) Pneumothoraxb) Hemothorax

a) Pneumothorax :1-Definition2-Etiology3-Radiographic Features4-Tension Pneumothorax

1-Definition :-Refers to the presence of air in the pleural space

2-Etiology :a) Primary Spontaneousb) Secondary Spontaneousc) Iatrogenicd) Traumatic

a) Primary Spontaneous :-A primary spontaneous pneumothorax is

one which occurs in a patient with no known underlying lung disease

-Tall and thin people are more likely to develop a primary spontaneous pneumothorax

b) Secondary Spontaneous :-When the underlying lung is abnormal , a

pneumothorax is referred to as secondary spontaneous

-There are many pulmonary diseases which predispose to pneumothorax including :

a) Cystic Lung Diseaseb) Parenchymal Necrosisc) Others

a) Cystic Lung Disease :1-Bullae , blebs2-Emphysema , asthma3-Pneumocystis carinii pneumonia (PCP)4-Honeycombing , end stage interstitial lung disease5-Lymphangiomyomatosis (LAM)6-Langehans cell histiocytosis (LCH)7-Ankylosing spondylitis (due to apical lung changes) 8-Cystic fibrosis

b) Parenchymal Necrosis :1-Lung abscess , necrotic pneumonia , septic

emboli , fungal disease & TB2-Cavitating neoplasm , metastatic osteogenic

sarcoma3-Radiation necrosisc) Others :-Catamenial : recurrent spontaneous

pneumothorax during menstruation , associated with endometriosis of pleura

c) Iatrogenic :1-Percutaneous biopsy2-Barotrama , ventilator3-Radiofrequency (RF) ablation of lung

massd) Traumatic :-Lung laceration-Tracheobronchial rupture

3-Radiographic Features :a) Upright Positionb) Supine Positionc) Other Positionsd) Size of Pneumothorax

a) Upright Position :-Visible visceral pleural edge see as a very thin sharp white

line-No lung markings are seen peripheral to this line-The peripheral space is radiolucent compared to adjacent

lung -The lung may completely collapse-The mediastinum should not shift away form the

pneumothorax unless a tension pneumothorax is present -Subcutaneous emphysema and pneumomediastinum may

also be present

Arrows point to thin white visceral pleural line whichis the single best sign for a pneumothorax

With SC emphysema

b) Supine Position :-Deep sulcus sign : Anterior costophrenic angle sharply delineatedWhen the patient is in the supine position , air in the

pleural space (pneumothorax) collects anteriorly and basally within the nondependent portions of the pleural space , if air collects laterally rather than medially , it abnormally deepens the lateral costophrenic angle and produces the deep sulcus sign

-Double diaphragm sign :Air may outline the anterior portions of the

hemidiaphragm and cause visualization of the anterior costophrenic sulcus

Deep sulcus sign

Deep sulcus sign

Double diaphragm sign

c) Other Positions :1-Lateral decubitus radiograph :-Should be done with the suspected side up-The lung will then fall away from the chest

wall2-Expiratory chest radiograph :-Lung becomes smaller and denser3-CT most sensitive

Lateral decubitus

Inspiratory filmExpiratory film (The image shows

increase in apparent size of the pneumothorax on the expiratory view compared to the inspiratory view , arrows show the pleura)

d) Size of Pneumothorax :Average distance (AD in cm) = (A + B + C)/3% Pneumothorax = AD (in cm) , e.g. AD of 1 cm corresponds to a 10%

pneumothoraxAD of 4 cm corresponds to a 40%

pneumothorax

4-Tension Pneumothorax :a) Definitionb) Radiographic Features

a) Definition :-occurs when intrapleural air accumulates

progressively in such a way as to exert positive pressure on mediastinal and intrathoracic structures

b) Radiographic Features :-Over expanded hemithorax-Shift of the mediastinum to the contralateral

side-Depression of the hemidiaphragm

Tension pneumothorax on left (blue arrow) is displacing the heart and mediastinal structures to the right (red arrow) ; this case also shows a deep sulcus sign on the left (yellow arrow)

The left lung is completely compressed (arrowheads) , the trachea is pushed to the right (arrow) , the heart is shifted to the contralateral side , note right heart border is pushed to the right (red line) , the left hemidiaphragm is depressed (orange line)

b) Hemothorax :1-Definition2-Etiology3-Radiographic Features

1-Definition :-Means blood within the chest , is a term usually

used to described a pleural effusion due to accumulation of blood

-If a hemothorax occurs concurrently with a pneumothorax it is then termed a hemopneumothorax

-A tension hemothorax refers to hemothorax that result from massive intrathoracic bleeding causing ipsilateral lung compression and mediastinal displacement

2-Etiology :a) Traumaticb) Spontaneous

a) Traumatic :-In 25-50% of patients with blunt chest

trauma and 60-80% of patients with penetrating wounds

b) Spontaneous :1-Primary Spontaneous :-Spontaneous pneumothorax , spontaneous

hemopneumothorax2-Secondary Spontaneous :a) Neoplasticb) Anticoagulant Medication c) Vascular Rupture

a) Neoplastic :1-Intra thoracic malignancy : -Usually occurs with thoracic wall tumorsThoracic wall schwanommasThoracic wall neurofibromas 2-Soft tissue tumors : -Sarcomas , thoracic angiosarcomas 3-HCC with thoracic invasion or thoracic metastases4-Lung cancer is a distinctly uncommon cause of

hemothorax even in the setting of pleural extension

b) Anticoagulant Medicationc) Vascular Rupture :1-Aortic Dissection2-Pulmonary AVM3-Pulmonary Infarction4-Thoracic Endometriosis

3-Radiographic Features :a) Plain Radiographyb) CT

a) Plain Radiography :-A large hemothorax may be seen as a

pleural effusion-It can be almost impossible to differentiate

a hemothorax from other causes of pleural effusion

There is complete opacification of the right hemithorax with slight shift of the trachea towards the left , fluid is seen tracking up the lateral margin of the thorax (red arrow) , the clue to the diagnosis is the bullet (blue circle)

Pneumohemothorax , after a stab injury . blood accumulates in the pleural space (hemothorax) , no pulmonary vasculature can be noted beyond the visceral pleural line in the upper lung due to the accumulation of air in the same space (pneumothorax)

b) CT :CT is useful in determining the nature of pleural

fluid in the setting of trauma by assessing the attenuation value , blood in the pleural space typically has an attenuation of 35-70 HU

-Pleural fluid attenuation measurement should be routine in the interpretation of chest trauma CT to distinguish simple fluid from acute blood

-In the setting of trauma , there may be other ancillary features such as pulmonary contusions & lacerations

7-Lung :1-Contusion2-Hematoma3-Laceration4-Fat Embolism5-Aspiration Pneumonia6-Foreign Body7-Pulmonary Edema8-Adult Respiratory Distress Syndrome

1-Contusion :a) Definitionb) Radiographic Features

a) Definition :-Refers to an interstitial and/or alveolar lung

injury without any frank laceration-It usually occurs secondary to non-

penetrating trauma

b) Radiographic Features :1-Plain Radiography2-CT

1-Plain Radiography :-Not sensitive-Faint patchy consolidative regions following

history of blunt trauma-Usually shows rapid improvement with time

usually days

2-CT :Typically seen as focal non segmental

(typically crescentic) areas of parenchymal opacification

-Can have sub-pleural sparing with smaller contusions which can be a distinguishing feature

-Commoner posteriorly and in lower lobe

2-Hematoma :-Usually appears following resolution of

contusion-Round well-defined nodule-Resolution in several weeks

3-Laceration :a) Definitionb) Classificationc) Radiographic Features

a) Definition :-Results from frank laceration of lung

parenchyma secondary to trauma , there is almost always concurrent contusion

-There is a linear tear (may be radiographically visible) that becomes round or ovoid (pneumatocele) with time

b) Classification :Type I : compression ruptureType II : compression shearType III : direct puncture / rib penetrationType IV : adhesion tears

c) Radiographic Features :1-Plain Radiography2-CT

1-Plain Radiography :Pattern can be similar to contusion but can

also have added rib fractures and pneumothorax

Flail Chest , CXR shows multiple rib fractures (black arrows) with some ribs fractured in two or more places , there is also a pulmonary contusion (red arrow) and subcutaneous emphysema (white arrow)

2-CT :-Regions of pulmonary contusion with added blebs

(pneumatocoeles) with air fluid levels-Due to normal pulmonary elastic recoil , lung

tissues surrounding a laceration often pull back from the laceration itself , this results in the laceration manifesting at CT as a round or oval cavity instead of having the linear appearance typically seen in other solid organs

Pulmonary Laceration , there is a soft tissue density in the right lower lobe (black circle) with several small air-containg cavities within it in a patient with recent trauma

Axial CT shows a hole in the lung with air-fluid level (arrow) surrounded by ground glass opacity (arrowheads) in a trauma patient , findings represent pulmonary laceration surrounded by contusion

4-Fat Embolism :a) Etiologyb) Radiographic Features

a) Etiology :-Lipid emboli from bone marrow enter

pulmonary and systemic circulation-1 to 2 days post-trauma-Resolves in 1-4 weeks-Frequently CNS is also affected

b) Radiographic Features :1-Plain Radiography2-CT

1-Plain Radiography :-Resembles pulmonary edema but normal

heart size and pleural effusion is uncommon

The chest x ray showed bilateral homogenous opacities

2-CT :-Three predominate patterns are observed :1-Ground-glass change with geographic

distribution2-Ground glass opacities with interlobular

septal thickening3-Nodular opacities

A 17 year old man with a comminuted femur fracture

Top , A: HRCT scan obtained the second day after injury shows ground-glass opacities

Bottom , B: HRCT at a lower level shows ground-glass opacities confined to some lobules with a sharp margination between areas of involved and noninvolved lung resulting in a geographic appearance , also noted is smooth and nodular interlobular septal thickening

A 19 year old man at 2 days after femur shaft fractures

Top , A: HRCT scan obtained at the lower lung zones reveals a predominantly peripheral distribution of ground-glass opacities associated with smooth and nodular septal thickening

Bottom , B: HRCT obtained at a lower level shows relative sparing of some secondary lobule

Top , A: HRCT obtained just below the tracheal bifurcation reveals a predominantly nodular pattern , note that bronchovascular bundles are thin and smooth

Bottom , B: HRCT obtained at the level of pulmonary veins shows similar pattern and severity of findings

5-Aspiration Pneumonia6-Foreign Body7-Pulmonary Edema :-Following blast injuries or head injury

(neurogenic edema) 8-Adult Respiratory Distress Syndrome :-Widespread air-space shadowing

appearing 24-72 hours after injury

8-Trachea & Bronchi :-Laceration or fracture :Initially surgical emphysema and

pneumomediastinum followed by collapse of the affected lung or lobe

9-Diaphragm : Rupturea) Incidenceb) Radiographic Features

a) Incidence :-In 3-7% of patients with blunt and 6-46% of

patients with penetrating thoraco-abdominal trauma

-Ninety percent of tears occur on the left side

b) Radiographic Features :1-Plain Radiography2-CT

1-Plain Radiography :-Herniated stomach or bowel above the

diaphragm-Pleural effusion-A supradiaphragmatic mass or a poorly

visualized or abnormally contoured diaphragm

2-CT :a) Direct CT Signs :1-Segmental Diaphragmatic Defect (focal and

abrupt loss of continuity in the diaphragm)2-Dangling Diaphragm (the free edge of the torn

diaphragm which curls inward from its normal course toward the center of the body forming a comma shaped or curvilinear structure)

3-Absent Diaphragm (absence of part or all of the hemidiaphragm without demonstration of a tear)

b) Indirect CT Signs Related to Herniation:1-Herniation through a Defect2-Collar Sign3- & 4-Hump and Band Signs5-Dependent Viscera Sign6-Sinus Cutoff Sign7-Abdominal Content Peripheral to the Diaphragm

or Lung Sign8-Elevated Abdominal Organs Sign

10-Mediastinum :a) Aortic Injuryb) Mediastinal Hematomac) Pneumomediastinum d) Hemopericardiume) Esophageal Rupture

a) Aortic Injury :1-Incidence2-Radiographic Features

1-Incidence :-90% of aortic ruptures occur just distal to

the origin of the left subclavian artery-More with blunt trauma

2-Radiographic Features :a) Plain Radiographyb) CT

a) Plain Radiography :1-Widening of the mediastinum 2-Abnormal aortic contour3-Tracheal displacement to the right4-Nasogastric tube displacement to the right of the

T4 spinous process5-Thickening of the right paraspinal stripe6-Depression of the left mainstem bronchus > 40°

below the horizontal 7-Loss of definition of the aortopulmonary window

Normal CXR Aortic Injury

b) CT :1-Non-Contrast :-May show indirect signs of aortic injury :a) Mediastinal hematomab) Periaortic fat strandingc) Other chest injuries

2-CTA :a) Signs of mediastinal hematoma :-Abnormal soft tissue density around the

mediastinal structures-Location is important , periaortic hematoma

much more suggestive of aortic injury than isolated mediastinal hematoma remote from the aorta

b) Signs of aortic injury :-Intraluminal filling defect (intimal flap or clot)-Abnormal aortic contour (mural hematoma)-Pseudoaneurysm-Extravasation of contrast

b) Mediastinal Hematoma :-Blurring of the mediastinal outline

c) Pneumomediastinum :1-Etiology2-Radiographic Features

1-Etiology :1-Blunt or penetrating chest trauma2-Secondary to thoracic , neck or retroperitoneal surgery3-Esophageal perforation4-Tracheobronchial perforation5-Vigorous exercise , child birth , valsalva maneuver6-Asthma7-TB 8-Perforation of a hollow abdominal viscous (with

extension of gas via the retroperitoneal space)

2-Radiographic Features :-Small amounts of air appear as linear or

curvilinear lucencies outlining mediastinal contours :

1-Thymic sail sign2-Air anterior to the pericardium3-Air around the pulmonary artery or its major

branches4-Air around the aorta or its major branches5-Double bronchial wall sign6-Subcutaneous emphysema

d) Hemopericardium :1-Definition2-Radiographic Features

1-Definition :-Accumulation of blood in the pericardium

2-Radiographic Features :->250 mL is necessary to be detectable-Subpericardial fat stripe measures >10 mm (a

stripe 1 to 5 mm can be normal)-Symmetrical enlargement of cardiac silhouette

(water-bottle sign)

Pericardial effusion on both chest radiograph and axial CT , Red arrow points to fat outside of pericardium , Green arrow points to pericardial space which is 8 mm in this patient (<4 mm is normal) , Yellow arrow  points to fat outside of heart and the blue arrow to the myocardium

Water bottle sign

e) Esophageal Rupture :1-Incidence2-Radiographic Features

1-Incidence :-Is a rare but serious medical emergency

with a very high mortality rate , especially if the diagnosis is delayed

-More in males

2-Radiographic Features :a) Plain Radiographyb) Contrast Enhanced Esophographyc) CT

a) Plain Radiography :-Chest radiographs are nonspecific and

usually show wide mediastinum , left pleural effusion or hydropneumothorax

-Pneumomediastinum is common but is a nonspecific finding

77 year old man with esophageal rupture , portable chest radiograph shows subtle retrocardiac opacity (arrow) and blunted left costophrenic angle (arrowhead) consistent with mild pleural fluid and overlying consolidation

b) Contrast Enhanced Esophography :-Extravasation of contrast material into the

mediastinum

c) CT :-Focal esophageal wall thickening-Periesophageal fluid collections-Free mediastinal air-Contrast extravasation into the

mediastinum and pleural space

77 year old man with esophageal rupture , CT of the abdomen and pelvis with oral and intravenous contrast , Axial (A) CT at the level of the aortic arch shows a dilated, air-and-fluid-filled thoracic esophagus (arrow) , Axial (B) and coronal (C) show extraluminal contrast and air (large arrows) extending to the left of the distal esophagus (e) , also note associated bilateral pleural fluid (B, pf) and overlying left-lung base atelectasis (B, arrowheads)

Acute mediastinitis in a patient with esophageal perforation

(a) CT+C shows esophageal wall thickening (arrow) and a posterior mediastinal air-fluid collection (arrowhead) abutting the esophagus

(b) CT+C shows the probable site of esophageal perforation (arrowhead) and esophageal wall thickening (arrow)