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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
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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 3 Neural crest
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
Heart • Heart • General Structure • Pericardium • 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 • Superior Vena Cava • Inferior Vena Cava • Pulmonary Arteries • Pulmonary Veins
Oesophagus • Esophagus • Enters at thoracic inlet • Posterior to trachea • Exits at esophageal hiatus
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: 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
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. EurRadiol. 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.