Download Imaging: Thoracic Trauma

Imaging:
Thoracic Trauma
Tony Tiemesmann
Diagnostic Radiology
Bloemfontein Hospital Complex
Introduction
• Vital Structures
– Heart, Great Vessels, Esophagus, Tracheobronchial
Tree, & Lungs
• 25% of MVC deaths are due to thoracic trauma
– 12,000 annually in US
• Abdominal injuries are common with chest trauma.
• Prevention Focus
– Gun Control Legislation
– Improved motor vehicle restraint systems
• Passive Restraint Systems
• Airbags
Anatomy 1
• Thoracic Skeleton
– 12 Pair of C-shaped ribs
• Ribs 1-7: Join at sternum with cartilage end-points
• Ribs 8-10: Join sternum with combined cartilage at 7th rib
• Ribs 11-12: No anterior attachment
– Sternum
• Manubrium
– Joins to clavicle and 1st rib
– Jugular Notch
• Body
– Sternal angle (Angle of Louis)
» Junction of the manubrium with the sternal body
» Attachment of 2nd rib
• Xiphoid process
– Distal portion of sternum
Anatomy 2
Anatomy 3
Neural
crest
Anatomy 4
• Mediastinum
– Central space within thoracic cavity
– Boundaries
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Lateral: Mediastinal pleura
Inferior: Diaphragm
Superior: Thoracic inlet
Posterior: Thoracic spine
Anterior: Sternum & costal cartilages
– Superior & Inferior mediastinum
– Inferior mediastinum
• Anterior
• Middle
• Posterior
Anatomy 5
• Structures (superior)
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Great Vessels
Oesophagus
Trachea
Nerves
– Vagus
– Phrenic
• Thoracic Duct
• Structures (inferior)
• Anterior – fat, lymph nodes
• Middle – heart, aorta, lower SVC, Trachea & main bronchi, lymph
nodes, pulmonary veins & arteries, phrenic nerve
• Posterior – Aorta, oesophagus, azygous & hemiazygous, thoracic duct,
vagus
Heart
• Heart
– General Structure
• Pericardium
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Surrounds heart
Visceral
Parietal
Serous
» 35-50 ml fluid
• Epicardium
– Outer Layer
• Myocardium
– Muscular layer
• Endocardium
– Innermost layer
4 weeks
6 weeks
Great Vessels
• Great Vessels
– Aorta
• Fixed at three sites
– Annulus
» Attaches to heart
– Ligamentum Arteriosum
» Near bifurcation of pulmonary artery
– Aortic hiatus
» Passes through diaphragm
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Superior Vena Cava
Inferior Vena Cava
Pulmonary Arteries
Pulmonary Veins
Oesophagus
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Esophagus
– Enters at thoracic inlet
– Posterior to trachea
– Exits at esophageal hiatus
Pathophysiology
• Blunt & Penetrating Trauma
– Results from kinetic energy forces
– Subdivision Mechanisms
• Blast
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Pressure wave causes tissue disruption
Tear blood vessels & disrupt alveolar tissue
Disruption of tracheobronchial tree
Traumatic diaphragm rupture
• Crush (Compression)
– Body is compressed between an object and a hard surface
– Direct injury of chest wall and internal structures
• Deceleration
– Body in motion strikes a fixed object
– Blunt trauma to chest wall
– Internal structures continue in motion
– Age Factors
• Pediatric Thorax: More cartilage = Absorbs forces
• Geriatric Thorax: Calcification & osteoporosis = More fractures
Cardiovascular 1
• Myocardial Contusion
– Occurs in 76% of patients with severe blunt chest trauma
– Right Atrium and Ventricle is commonly injured
– Injury may reduce strength of cardiac contractions
• Reduced cardiac output
– Electrical Disturbances due to irritability of damaged myocardial cells
Cardiovascular 2
• Pericardial Tamponade
– Restriction to cardiac filling caused by blood or other
fluid within the pericardium
– Occurs in <2% of all serious chest trauma
• However, very high mortality
– Results from tear in the coronary artery or penetration of
myocardium
• Blood seeps into pericardium and is unable to escape
• 200-300 ml of blood can restrict effectiveness of cardiac
contractions
– Removing as little as 20 ml can provide relief
Cardiovascular 3
• Myocardial Aneurysm or Rupture
– Occurs almost exclusively with extreme blunt thoracic
trauma
– Secondary due to necrosis resulting from MI
– Signs & Symptoms
• Severe rib or sternal fracture
• Possible signs and symptoms of cardiac tamponade
• If affects valves only
– Signs & symptoms of right or left heart failure
• Absence of vital signs
Cardiovascular 4
• Traumatic Aneurysm or Aortic Rupture
– Aorta most commonly injured in severe blunt or penetrating
trauma
• 85-95% mortality
– Typically patients will survive the initial injury insult
• 30% mortality in 6 hrs
• 50% mortality in 24 hrs
• 70% mortality in 1 week
– Injury may be confined to areas of aorta attachment
– Signs & Symptoms
• Rapid and deterioration of vitals
• Pulse deficit between right and left upper or lower extremities
Cardiovascular 5
• Other Vascular Injuries
– Rupture or laceration
• Superior Vena Cava
• Inferior Vena Cava
• General Thoracic Vasculature
– Blood Localizing in Mediastinum
– Compression of:
• Great vessels
• Myocardium
• Esophagus
Oesophagus
• Traumatic Esophageal Rupture
– Rare complication of blunt thoracic trauma
– 30% mortality
– Contents in esophagus/stomach may move into
mediastinum
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Serious Infection occurs
Chemical irritation
Damage to mediastinal structures
Air enters mediastinum
– Subcutaneous emphysema and penetrating trauma
present
Imaging: Radiography
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NB NB
Delay only in life-threatening conditions
Haemo/Pneumothorax
Fractures (ribs - flail chest)
Mediastinum – widened, air
Diaphragmatic rupture
Foreign bodies
Imaging: Computed tomography
• Blunt lung trauma – blood in bronchi, interstitial blood
• Cardiac & major vessel trauma (with or without angio)
– critical area to evaluate on CT scans is the aorta at the level of the
left main pulmonary artery (90% of all CT-detected aortic injuries
begin at or just above this level and that 85% of aortic injuries end
at or just below it)
• CTA
• Bony elements & surrounding tissue
Imaging: MRI
• Stable patients
• CT unequivocal
• NB: vascular and spinal injuries
Imaging: Ultrasound
• Quick & non-invasive
• FAST (focussed assessment for sonographic evaluation of
the trauma patient)
• Percardiac – percardiocentesis
• Sternum
• Pleural
• Pulmonary contusion
• Diaphragm
• NB: Degree of confidence
Imaging: Echocardiography
• Acute blunt cardiac injury – chamber disruption, valvular
incompetence, coronary artery thrombosis, ventricular
aneurysm formation, myocardial contusion
• Detectable functional changes – cardiac function, motion
abnormalities of the cardiac wall, pericardial effusions,
valvular injury
Imaging: Angiography
• Widened mediastinum on CXR (3% aortic injury)
• Aortogram – rupture/pseudoaneurysm
Imaging: Nuclear medicine
• Continuing symptoms with no radiological signs
• Skeletal - technetium-99m diphosphonate
• Cardiac - thallium-201 chloride
Trauma Imaging 1
Trauma Imaging 2
Trauma Imaging 3
Trauma Imaging 4
Trauma Imaging 5
Trauma Imaging 6
Trauma Imaging 7
Trauma Imaging 8
Trauma Imaging 9
Trauma Imaging 10
References
• Kaewlai R, Avery L, Asrani A, Novelline R. Multidetector CT of Blunt
Thoracic Trauma. RadioGraphics 2008; 28:1555–1570.
• Jin W, Yang DM, Kim HC, Ryu KN. Diagnostic values of sonography for
assessment of sternal fractures compared with conventional
radiography and bone scans. J Ultrasound Med. Oct 2006;25(10):12638; quiz 1269-70.
• Gavelli G, Canini R, Bertaccini P. Traumatic injuries: imaging of
thoracic injuries. Eur Radiol. Jun 2002;12(6):1273-94.
• Khan AL et al. Trauma thoracic imaging. Medscape Oct 2011.
• DiMaio VJM, Dana SE. Handbook of forensic pathology 2nd ed. CRC
Press. 2006.