Introduction to trauma imaging Guidelines and highlights for different

imaging techniques.

ASSIUT UNIVERSITY TRAUMA COURSE (AUTC) MARCH 2010.

Dr. Hazem Abu Zeid Yousef MD

Lecturer of Radiodiagnosis.

INTRODUCTION

More than 3000 people die on the world's roads every day. Tens of millions of people are injured or disabled every year. Road traffic accidents are the leading cause of death in the first study of global patterns of death among people aged between 10-24 years of age (WHO 2009).

Time is the enemy for trauma victimsTime is the enemy for trauma victimsTrauma surgeons are ruled by the Trauma surgeons are ruled by the

““Golden Hour”.Golden Hour”.

Time is of the Essence in Trauma

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PART (1)

HEAD TRAUMA

HEAD INJURIES.“Early imaging, rather than admission and observation for neurological deterioration, will reduce time to detection for life threatening complications and is associated with better outcomes (NICE clinical guideline 2008).

CLICK HERE TO ADD TEXTSKULL RADIOGRAPHY (SXR)

AdvantagesQuickNo need for radiologistLow dose of radiation (0.14mSv)Inexpensive

DisadvantagesIncreased workloadInconclusive

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SYSTEMATIC INSPECTION OF THE SXR

Step (1) : Scrutinize the site of the injury.

Step (2) : Look for:

Fissure fracture.

Depressed fracture.

Fluid level in the sphenoid sinus.

Step (3) : Look for less common finding (e.g. pneumocephalus).

Fissure versus VM Fissure black VM gray.

VM is branching.

VM has sclerotic edges.

Fissure versus suture

The fracture is more radiolucent than the other sutures, has no serration along its edges, and is blind ending.

Depressed fractures are often difficult to see. Look for increased or double density

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This study shows that skull x rays can successfully be abandoned in children aged 1 to 14 years with head injuries without any significant increase in admission rate, radiation dose per head injury, or missed intracranial injuries. We suggest that routine skull x rays have no place in the paediatric emergency department for those children aged 1 year and over. Mechanism of head injury (falls of more than 1 metre and road traffic accidents carrying higher risk), a history of drowsiness or loss of consciousness, and a reduced score on the Glasgow coma scale are probably the most important indicators of serious head injury in children (Reed wt al., 2005).

Head CT

Advantages for TBI include: availability, short scan times, detailed anatomic information - including evaluation of facial and temporal bone fractures.

Less sensitive for small parenchyma bleeds such as those seen

with DAI.

CLICK HERE TO ADD TEXTAnatomic Patterns of Traumatic Brain injury

Blood: epidural, subdural, parenchyma, ventricular, Blood: epidural, subdural, parenchyma, ventricular, and subarachnoid.and subarachnoid.Direct injury to brain – frontal lobe and anterior Direct injury to brain – frontal lobe and anterior temporal lobe.temporal lobe.Sheering injury: deformation of brain causing diffuse Sheering injury: deformation of brain causing diffuse axonal injury.axonal injury.

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Diffuse axonal injury

Diffuse axonal injury (DAI) is a major form of traumatic brain injury and is caused by shearing stress primarily in white matter). Various outcomes are reported (ie, learning disorders, moderate to severe disability, and vegetative state) but were unable to correlate the extents of early injury with the prognoses.

Among patients eventually proven to have DAI, 50-80% demonstrate a normal CT scan upon presentation. Delayed CT scanning may be helpful in demonstrating edema or atrophy, which are later findings. Small petechial hemorrhages located at the gray-white matter junction, as well as in the corpus callosum and brainstem, are characteristic of CT-scan findings in the acute setting.

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The ability to detect DAI by using imaging, whether the lesions are hemorrhagic or nonhemorrhagic, has substantially improved with the advent of MRI. MR imaging has been helpful in defining patterns of injury in adults with DAI—depicting involvement predominantly in the frontal white matter, corpus callosum, brainstem, and diencephalon.

Figure 1. Patient 2.

Tong K A et al. Radiology 2003;227:332-339

©2003 by Radiological Society of North America

Figure 2. Patient 4.

Tong K A et al. Radiology 2003;227:332-339

©2003 by Radiological Society of North America

Figure 3. Patient 2.

Tong K A et al. Radiology 2003;227:332-339

©2003 by Radiological Society of North America

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PART 2

CHEST TRAUMA

After chest trauma, imaging plays a key role for both, the primary diagnostic work-up, and the secondary assessment of potential treatment. Despite its well-known limitations, the AP chest radiograph remains the starting point of the imaging work-up. Adjunctive imaging with CT, that recently is increasingly often performed on MDCT units, adds essential information not readily available on the CXR. This allows better definition of trauma-associated thoracic injuries not only in acute traumatic aortic injury, but also in pulmonary, tracheobronchial, cardiac, diaphragmal, and thoracic skeletal injuries.

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• Blunt

• Penetrating

• Explosion Related

Chemical Agent Related

Biological Agent Related

Types of Chest trauma

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Trauma Chest Radiograph

• Usually AP, often supine, frequently in poor inspiration.

• So, a challenge to interpret.

CT ChestMore sensitive and specific

CT Chest: Reformat

The new MDCT scanners do awesome reformats without additional scanning.

Blunt chest trauma

• Factures and dislocations

• Air where it shouldn’t be

• Hemothorax

• Pulmonary contusion and laceration

• Diaphragm injuries

Fractures and Dislocations

• Spine

• Ribs

• Clavicles

• Sternum

• Shoulders

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• Spine Injuries

• Look for loss of alignment, fractures and paraspinal hematoma.

• The findings may be very subtle.

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• CT is the imaging modality of choice for evaluation of these injuries.

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CLICK HERE TO ADD TEXTSimple rib fractures are frequently encountered on chest radiographs and rarely require further studies. However, complication of rib fractures such as pneumothorax, hemothorax, lung contusions, and lacerations are of more important clinical impact than the fracture itself

Multiple fractures of the same rib or simple fractures of three or more contiguous ribs comprise a flail segment of the chest wall. This results in paradoxical motion and inhibits normal respiratory motion, leading to impaired ventilation.

CLICK HERE TO ADD TEXTSterno-Clavicular Dislocations

• Anterior: Not much of a problem.

• Posterior: Less common; can injure great vessels or trachea.

Sterno-clavicle dislocation: CT

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Shoulder Injuries

Look particularly for dislocations and scapula fractures

Sternum Fractures

• Not usually a problem.

• Controversial association with myocardial injury.

AIR where it shouldn’t be

• Pneumothorax

• Pneumomediastinum

• Subcutaneous emphysema

• Systemic venous air embolism

• Pneumopericardium

• Pneumoperitoneum/retroperitoneum

PNEUMOTHORAX

• Simple

• Tension

• Open

PNEUMOTHORAX: CT

Much more sensitive than plain films. Even a small traumatic pneumothorax is important, especially if patient mechanically ventilated or going to OR: A simple pneumothorax can be converted into a life- threatening tension pneumothorax.

Pneumothorax: Simple

• Erect AP/PA view best• Visceral pleural line• No vessels or markings• Variable degree of lung

collapse• No shift

PNEUMOTHORAX: Tension

• Erect AP/PA view best.

• Shift of mediastinum away from PTX side.

• Depressed hemidiaphragm.

• Degree of lung collapse is variable.

PNEUMOTHORAX: Diagnostic limitations of supine view

Supine AP view has limited sensitivity: 50%.Deep sulcus sign.Too sharp heart border/hemidiaphragm sign.Increased lucency over lower chest.Subpulmonic air sign.Can see vessels.

PNEUMOMEDIASTIUM

• Usually from ruptured alveoli.

• Can also be from trachea, bronchi, esophagus, bowel and neck injuries.

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Signs:

• Linear paratracheal lucencies

• Air along heart border

• “V” sign at aortic-diaphragm junction

• Continuous diaphragm sign

PNEUMOMEDIASTIUM

Surgical Emphysema

Pneumopericardium

Penetrating injuries

Pneumoperitoneum

Systemic venous air embolism

HEMOTHORAX

• Venous or arterial bleeding

• 60% controlled by chest tube, 40% need operative management

• Can miss hundreds of cc’s on supine film

• Can be tension

Traumatic aortic rupture

PULMONARY CONTUSION and LACERATION

Contusion: Blood in intact lung parenchymaLaceration: Blood in torn lung parenchymaCan’t tell difference on chest film. Contusions peak in 2-3 days, begin to resolve in a week; lacerations take much longer to resolve and may leave scars

The tear in the lung can fill

with blood or air.

CT: Pulmonary laceration

DIAPHRAGM Injuries

• 5% of major blunt trauma, also thoraco-abdominal penetrating trauma

• Left clinically injured more than right 60/40

• Sensitivity of Chest film 40%. CT better, but still misses some

• Sure signs: NGT through g.e. junction then up into chest, and hollow viscus above diaphragm

• Less significant signs: Indistinct diaphragm, effusion, atelectasis

PENETRATING TRAUMA

Gun-shot wounds:Caliber, weight, construction of bulletVelocityTissue impactedKnife wounds:All low energy, small diameter wounds. Frequently, superficial stab or slash.Look for lung laceration, pneumothorax, hemothorax, pneumomediastinum, abnormal contour of mediastinum or heart.Path of wound is straight.

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SPINAL TRAUMA

Objectives

• Clinical indication for each imaging modality

• Identify anatomy of the spine• Approach to spine radiography

interpretation• Classification of spine injuries

Canadian C-Spine Rule for selective ordering of cervical spine imaging

Stiell, I. G et al. BMJ 2009;339:b4146

GCS below 13 on initial assessment. Has been intubated. Plain film series is technically inadequate (for example, desired view unavailable), suspicious or definitely abnormal. Continued clinical suspicion of injury despite a normal X-ray. The patient is being scanned for multi-region trauma.

Who gets CT

Who gets MRI

Unexplained neurologic symptoms/signsFor visualizing soft tissues, neural elements and unsuspected disk herniationTo differentiate cord edema, hemorrhage, and infarctionTo better characterize epidural hematoma

RADIOGRAPHY for primary cervical spine screening

• Minimum standard views– Lateral through C7

– AP

– Odontoid

• Supplementary views• Bilateral obliques

– Swimmer’s

– Flex ion and extension

Lateral ViewBase of the occiput should be visualizedJunction of C7-T1 must be visualizedA swimmer’s view taken with one arm extended over the head can be helpful

AP view

Must include the spinous processes of all the cervical vertebrae from C2 trough T1.OM viewMust show relationship of the lateral masses of C1 and the odontoid process.

1 = anterior vertebral line

2 = posterior vertebral line

3 = spinolaminar line

4 = posterior spinous line

NORMAL CERVICAL SPINENORMAL CERVICAL SPINE

RP

Predental spacePredental space • 3mm or less (4-5mm in children)

C2-C3 pseudosubluxationC2-C3 pseudosubluxation • 3mm or less (4-5mm in children)

Retropharyngeal spaceRetropharyngeal space • < 6mm at C2

• < 22mm at C6

• For children 1/2 to 2/3 vertebral body distance anteroposteriorly

Angulation of spinal column at Angulation of spinal column at any single interspace levelany single interspace level

• < 11 degrees

Cord dimensionCord dimension • 10-13mm

Cervical Spines NormsCervical Spines Norms

Mechanism of FracturesHyperflexion Hyperextension Axial compression

Classification

Classification

Type of Injury Fractures Stability

Flexion Anterior subluxation 

Unilateral facet dislocationBilateral facet dislocationWedge compression fractureFlexion teardrop fractureClay Shoveler's fractureOdontoid

stable or delayed instability

stableunstablestableunstablestableunstable

Extension Hangman's fracture  unstable

Compression Jefferson fractureBurst fracture

unstablestable

CT versus Radiography

Vandermark claimed:Vandermark claimed:Well positioned and optimally exposed radiographs Well positioned and optimally exposed radiographs disclose 95% of clinically significant C-spine disclose 95% of clinically significant C-spine fractures.fractures.However – However – these high quality studies are often these high quality studies are often impossible to obtain impossible to obtain and and pt’s at highest risk are most pt’s at highest risk are most likely to have technically compromised imaging. likely to have technically compromised imaging. 1996 Nunez et al 1996 Nunez et al 40% of Fx’s40% of Fx’s missed on rad missed on rad later later revealed on CTrevealed on CT 1/3 had clinically significant or unstable Fx’s1/3 had clinically significant or unstable Fx’s

• Helical CT– Faster?

– More Sensitive?

– Cost effective/more expensive?

• Conventional Rad– Slower?

– Less sensitive?

– Less expensive?

So, which do you choose?

HighHigh (fracture risk of 11.2%) = severe head (fracture risk of 11.2%) = severe head injury, focal neuro deficits, >50 yrs w/ high-injury, focal neuro deficits, >50 yrs w/ high-energy mechanism of injury.energy mechanism of injury.ModerateModerate (4.2%)= >50 yrs w/ a moderate-energy (4.2%)= >50 yrs w/ a moderate-energy mechanism or <50 w/high energy.mechanism or <50 w/high energy.LowLow (2.1%)= <50 w/ moderate energy (2.1%)= <50 w/ moderate energy mechanism of injury.mechanism of injury.

Blackmore et al (2001) Risk stratification

Blackmore et al’s recommendation

CT should be considered as THE PRIMARY CT should be considered as THE PRIMARY

cervical spine screening modality in selected cervical spine screening modality in selected

victims of major trauma who are examined in victims of major trauma who are examined in

high-volume urban ED’s.high-volume urban ED’s.

Case 1

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http://www.radiologyassistant.nl/images/4902c748ce312flex6.jpg

CLICK HERE TO ADD TEXT• Unilateral Facet Dislocation

Hyperflexion + rotationSuperior facet slides over inferior facet and becomes lockedAnterior subluxation of superior vertebral body –25% AP diameter Stable injury30% with associated neurologic deficitMRI: disk extrusion leading to cord compression

Case (2)

http://www.radiologyassistant.nl/images/49034c6934fe3flexy.jpg

Bilateral Facet Dislocation

Extreme hyperflexionAnterior dislocation of articular masses (disruption of

posterior ligament complex,PLL,disk and ALL).Complete dislocation: dislocated vertebra anteriorly displaced ½ of AP diameter of vertebral bodyUnstable ( high incidence of cord damage)

Case (3)

Case (4)

Flexion Tear Drop

Flexion+compression (MVA)Teardrop fragment comes from the anteroinferior aspect of the vertebral bodyLarger posterior part displaced backward into the spinal canalFacets joints and interspinous distances usually widened, disk space may be narrowed70% of patients with neurologic injuriesUnstable fracture (complete disruption of ligaments and anterior cord syndrome

Case (5)

Hangman’s fracture

Most common cervical spine fractureUsually hyperextensionUnstable, however seldom associated with cord injury (AP diameter of spinal canal greatest at C1/C2 level and # pedicles allow decompression)Hangman’s + uni/bilateral facet dislocation: high rate of neurologic complications

Case (6)

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Hyperextension injury

Widening of disk space anteriorly and narrowing posteriorly“open book”Central cord injury= disproportionated weakness in arms and normal strength in the legsInjuries can be devastating, however are uncommon hemorrhagic

Case (7)

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Extension Teardrop Fracture

ALL pulls bony fragment away from inferior aspect of the vertebra because sudden extensionFragment is true avulsion x fragment from flexion teardrop (compression)Lower cervical spineCentral cord syndrome (buckling of ligamenta flava into spinal canal)Stable in flexion; highly unstable in extension

Case (8)

Jefferson Fracture

Burst fracture of ring of C1Axial loading in the occiputNo associated neuro deficts ( C1 ring is wide!)> 2mm dislocation of lateral masses of C1 or odontoid view is diagnostic, 1-2 mm is equivocal ( rotation of head?)Predental space > 3 mm: disruption of transverse ligament1/3 associated with C2 fracture

Thoracic Spine Injuries

RigidSpinal canal narrower than cervical or lumbar spine

Large spinal cord diameter relative to canal diameter increases the risk of cord injury

Injury, usually significant (complete), less common than in other regionsAssociation between fractures of the thoracic spine and severe pulmonary injuries, mediastinal hemorrhage

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Compression fracture

Injury to anterior column due to anterior or lateral flexion

Middle and posterior columns remain intactX-ray - decreased height anterior vertebral body, post body height normalAmount of anterior compression usually less than 40% of post body heightClinically - stable, cord injury rare

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• Unstable if: – vertebral height > 50%

– Angulation more than 20 degrees

– Multiple adjacent Loss of compression fractures

Burst• Disruption of the middle column• Mechanism- axial loading • Varying degrees of retropulsion

into the neural canal

• X-ray- spreading of post elements• If post elements involved- 50%

have neuro injury • Neurologic injury more common in:

– Loss of vertebral ht > 50%– Angulation > 20 deg– Canal compromise more than 40%

Lumbar Spine Injury

• Lower lumbar spine is the most mobile

• Isolated fractures of the lower lumbar spine rarely result in complete neurologic injuries

• Injuries: complete cauda equina lesion or isolated nerve root injuries

Spinal cord injury (SCI)

Spinal cord injuryThere are two types of injury to the spinal cord:

• Non-hemorrhagic with only high signal on MR due to edema.

• Hemorrhagic with areas of low signal intensity within the area of edema.

• There is a strong correlation between the length of the spinal cord edema and the clinical outcome.

• The most important factor however is whether there is hemorrhage, since hemorrhagic spinal cord injury has an extremely poor outcome.

Midsagittal (a) T1-weighted and (b) T2-weighted MR images obtained in 45-year-old man with acute traumatic C5 through C6 mild SCI after a fall show the distances of the spinal canal and spinal cord at the injury site (Di and di, respectively), one segment below the injury site (Db and db, respectively), and one segment above the injury site (Da and da, respectively) used to (a) estimate the MCC and (b) measure spinal canal compression.

©2007 by Radiological Society of North America

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