Radiology of Trauma Flashcards
What does imaging constitute in terms of head trauma?
Important part in modern day practice
What has a lot of guidelines been looking at?
Indication for imaging
When is there enhanced role for CT?
After head injury
What is enhanced role for CT after head injury advocated by?
- Neurosurgeons in 1990 and 1998, 1999 guidelines from RCSEng
Historically, what is the only imaging that are performed in form of head trauma?
Skull radiographs
Extremely unreliable
Variable reliability
What is the reliability of head trauma?
ER clinicians miss 13-23%
What does skull radiographs have?
Low sensitivity
What is CT sensitivities and specifities 100% for?
Detecting and locating a surgically significant focal intracranial lesion
What is the effect of Admissions?
- Most patients would be admitted for observations
- Specialists observations are required
- Only 1-3% develop life-threatening intracranial pathology
- Remainder home after 48 hours observation
- Significant resource burden on the NHS
- Quality of observations
- Limited emergency neurosurgical beds in the UK
- Secondary deterioration delayed with routine neurological observations
What is the morbidity of Head trauma?
- Mismanage head injury
- High level of disability following minor/mild head injury
- Far exceeds capacity of UK neuro-rehabilitation services
What are the imaging modalities for head trauma?
SXR limited usefulness:
- Calvarial fractures
- Penetrating injuries
- Radiopaque foreign bodies
What is the Computed Tomography (CT)?
- Main: imaging head trauma in acute setting
What is CT sensitive for?
Mass effect (brain shift)
Ventricular size
Bone Injuries
Acute haemmorhage
What is the limitations for CT including insensitivity in detecting?
- Small and non-haemorrhagic lesions (e.g. contusion)
- DAI
- Detecting increased ICP or cerebral oedema
- Early demonstration of HIE
What is MRI good for?
Looking at tissue discrimination therefore finer points of tissue injury
What does MRI look at?
Specific sequences to look at by-product of haemorrhage [determining the extent of damage]
What is DWI used for?
Impeding infarction or established infarction
What is MRI sensitive for?
Subacute and chronic brain injuries
-Hemosiderin-sensitive T2W GRE + SWI sequences
What does DWI improve?
Detection of acute infarction
What is FLAIR imaging sensitive for?
Subarachnoid haemorrhage and lesions bordered by CSF
What is required for non-haemorrhagic primary lesions (contusions) or secondary effects (oedema, HIE, DAI)?
Superior contrast resolution
What is MRI hindered by?
- Limited availability in acute trauma setting
- Long Imaging times - sensitivity to patient motion
- Relative insensitivity to subarachnoid haemorrhage
- Medical devices incompatability unless MRI-specific
- Risk of in-dwelling devices or forgein bodies
What are examples of foreign bodies?
- Cardiac pacemaker
2. Cerebral aneurysm clip
What is angiography?
Look at vessels in the brain, different various form
When do you do angiogram?
High index of suspicion for vascular injury and treat by stemming the floor of haemorrhage or by repairing it
What should be used in the case of penetrating trauma, skull base fractures or trauma to the neck there is a distinct possibility of vascular injury?
- CT
- MR angiography
sequences
What is CT/MR good for?
Primary vascular injuries
blood injuries by arterial dissection
What is vascular injuries typically seen in?
- Penetrating trauma
- Base skull fracture
- Trauma to the neck
What is less invasive screening tools for traumatic vascular lesions?
- CTA
2. MRA
What remains the gold standard for dissection depiction?
Angiography
What are other imaging modalities suggested for assessment of cognitive and neuro-psychologic disturbances and reocvery?
- PET
- SPECT
- Xenon-enhanced CT
- Functional MRI
What are the investigated criteria?
- GCS
- Vomitting and headache
- Amnesia
- Ethanol or Drug intoxication
- Age
- Anticoagulation or coagulopathies
Amnesia
- Common after mild head injury
- Longer episodes, greater chance of haemorrhage
- SPECT study/- amnesia >33min- bilateral cerebral hypoperfusion
What did up to 8% of alcohol intoxicated patients have?>
Intracerebral injury
What are the guidelines for Imaging?
- National Institute for Health and Clinical Excellence (nice) – January 2014 (updated) CG176
- American College of Radiology (ACR) APPROPRIATENESS Criteria 2007
- American Association of Neurological Surgeons 2001
- Canadian CT head rule study 2001
- New Orleans Criteria 2000
What are examples of primary neuronal injury?
- Cortical contusion
- Diffuse Axonal Injury (DAI)
- Primary brain stem injury
What are examples of primary haemorrhage?
- Subarachnoid Haemorrhage
- Subdural haematomas (SDH)
- Extra dural Haematomas (EDH)
- Intracerebral Haematomas
What is cortical contusion?
- Consequence of direct trauma against the skull
2. Acceleration/Deceleration
What is Diffuse Axonal Injury/
- Non-linear accelerator via accelerative force that is applied to the brain
- There is differential momentum of brain tissue
- Grey and white matter move at different rates in different directions and cause shearing force and vascular injury
- Happens throughout the brain with different densities of tissues
What is Subarachnoid Haemorrhage?
- Intracranial arterial rupture
- Most common in aneurysm
- Rupturing of intracranial arteries that can happen because of shear and trauma
What is Subdural Haemorrhage?
- Bridging veins within subdural space
- Causes mass effect
- Slower in neurology onset
What is Intraventricular Haemorrhage?
- Consequence of severe diffuse shear injury
What is Extra-dural haemorrhage?
- Arterial bleed from a dural arterial supply
- Tend to have a slightly different configuration
- Associated with fractures
What is Parenchymal Haemorrhage?
- Secondary vascular type injury
- Injuries to the vessel that supply the brain
- Cause a little focus of haemorrhage
- Larger and more discrete haemorrhage -frontal and directional impact
What is vascular injuries?
- Traumatic arterial and venous injuries more prevalent after head trauma than generally believed
What are examples of vascular injuries?
- Dissections
- Laceration
- Occlusion
- Pseudoaneurysms
- Ateriovenous fistulas
What is vascular injuries caused by?
Basal skull fractures
When is surgery for fractures done?
- Depressed skull more than full thickness of the skull
- Open fractures that give rise to pneumocephalus
- Relieve or prevent CSF leakage, infection, haemorrhage or vascular compromise
- SXR, CT imaging modality of choice
- CT, contrast CT or radionuclide cisternography used for detecting sites of CSF leaks
- Nuclear medicine study: put a radionuclide into the CSF space and watch it seep out
What do foreign bodies cause?
Several mechanisms depending on size and velocity:
- Direct laceration
- Shock-wave transmission
- Cavitation
What does imaging serve to do?
Detect, localise, aid removal and assess extent of damage
When is secondary injury most commonly encountered?
- Territorial arterial infarction
- Prolonged transtentorial and subfalcine herniations
- Direct vascular laceration, thrombosis and embolism
What is chronic sequelae of head injury characterised by?
- Parenchymal atrophy
- Residual haemoglobin degradation products
- Wallerian-type axonal degeneration
- Demyelination
- Cavitation
- Microglial scarring
What is guidance for injury?
- Anterior 2/3 vertebral body, disc and the ALL
- Posterior 1/3 vertebral body, disc and PLL
- Pedicles, transverse processes, laminae, articular facets and spinous processes
- If 2 columns disrupted = unstable injury
- Nice Guidelines NG41 – assessment of clinical severity by the Canadian C-spine rule
What is Spine multi-modal Imaging?
- Children (<16):
- MRI if strong suspicion of spinal cord or column injury
- X-ray if do not fulfil the criteria for MRI
- Adults:
- CT if indicated by Canadian C-spine rule or neurology
- CT if strong suspicion of T or L spine injury
- X-rays otherwise
- MRI where CT cannot explain neurology
What is the mechanism of Injury (Cervical)?
- Hyperflexion
- Hyperextension
- Axial compression
What are the upper cervical spine fractures?
- Complex flexion/extension
- Atlanto-Occipital Dislocation
- Odontoid Peg Fractures
- Extension
- Hangman’s fracture
- Vertical compression
- Jefferson’s fracture
What is the Lower Cervical Spine Fractures?
• Flexion • Flexion teardrop fracture • Wedge compression fracture • Clay shoveler’s fracture • Bilateral facet joint dislocation • Flexion rotation - Unilateral facet joint dislocation • Vertical compression - Burst fracture
What is soft tissue spinal injuries ?
- Anterior Subluxation
- Ligamentous injuries
- Cord contusion
- Brachial plexus injuries
- Vertebral arteries
What is Thoracolumbar spine fractures?
- Wedge compression Fractures
- Burst Fractures
- Chance Fractures
- Spondylolisthesis
- Sponylolysis
