Imaging: Thoracic Trauma Tony Tiemesmann Diagnostic Radiology Bloemfontein Hospital Complex.
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Transcript of 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 4
• Mediastinum– Central space within thoracic cavity– Boundaries
• 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)• 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
6 weeks4 weeks
Heart
• Heart– General Structure
• Pericardium– Surrounds heart– Visceral– Parietal– Serous
» 35-50 ml fluid• Epicardium
– Outer Layer• Myocardium
– Muscular layer• Endocardium
– Innermost layer
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– Superior Vena Cava– Inferior Vena Cava– Pulmonary Arteries– Pulmonary Veins
Pathophysiology
• Blunt & Penetrating Trauma– Results from kinetic energy forces– Subdivision Mechanisms
• Blast– 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• Serious Infection occurs• Chemical irritation• Damage to mediastinal structures• Air enters mediastinum
– Subcutaneous emphysema and penetrating trauma present
Imaging: Radiography
• 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: 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
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):1263-8; 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.