This document discusses traumatic brain injury and the use of various imaging modalities like CT and MRI to evaluate brain injuries. It begins by outlining the aims and providing background on head trauma. It then covers classifications of traumatic brain injury, clinical indications for imaging, and different imaging techniques. The bulk of the document describes various abnormalities that can be seen on imaging after brain trauma, including extraaxial hemorrhages, intraaxial injuries, and brain herniations. It provides details on indications for CT and MRI and emphasizes that CT is usually the first-line imaging modality for emergency brain evaluation.

1. Dr. Sunil Kumar Sharma
Senior Resident
Dept. of Neurology
GMC Kota

2. Aim
To understand Indications and select the appropriate
imaging modality
To identify common traumatic emergency
abnormalities of brain.
To determine an immediate life threatening
abnormality on a CNS imaging

3. INTRODUCTION
Head trauma is the leading cause of death in people
under the age of 30.
Males have 2-3 x frequency of brain injury than
females
Due mainly to motor vehicle accidents and assaults

4. OUTLINE
Classification of traumatic brain injury
Clinical indications for imaging
Imaging technique
Extraaxial hemorrhage
Intraaxial injury
Brain herniations

5. Classification of traumatic brain
injury

6. Traumatic Brain Injury
Classification -
Primary & Secondary
Mechanism of injury-Penetrating, Blunt
Location-Intraaxial, Extraaxial
Clinical severity, GCS -Mild, Moderate, severe

7. Classification of TBI
Primary
Injury to scalp, skull fracture
Surface contusion/laceration
Intracranial hematoma
Diffuse axonal injury, diffuse vascular injury

8. Contd..
Secondary
Hypoxia-ischemia
swelling/edema
raised intracranial pressure
Meningitis/abscess

10. Imaging Modalities
Plain Radiography
Ultrasound
CT
MRI
Radionuclide studies
Angiography

11. Conventional X-rays
Uses a form of Ionizing radiation
Good in evaluating air containing structures, bones
and calcifications
Limitations
No depth information
Low soft tissue contrast
Radiation

13. Computed Tomography
Uses Ionizing radiation.
Cross-sectional image
Principle based on differential x-ray beam
attenuation by tissue
Image contrast, displayed as Gray scale –
Density/attenuation
Low attenuation-Darker
High Attenuation-Whiter

14. APPROACH TO CT BRAIN
Look at the scout film: ? Fracture of upper
cervical spine or skull
Look at bone windows to see fractures
Look for brain asymmetry
Look at sulci, Sylvian fissure and cisterns to
exclude subarachnoid hemorrhage
Look for subdural collection
Determine if mass is intraaxial (in the brain) or
extraaxial (outside)

15. Advantages of CT
High sensitivity for calcification
Easier and faster to perform.
Most sensitive for detection of acute hemorrhage
Increasing availability
No contraindications to emergency patient scanning
Quickest & most efficient screening technique in
acute traumatic setting

16. Disadvantages of CT
High radiation dose per examination
Children are more sensitive to radiation induced
cancers than adults
Bone marrow, thyroid, breast, and lung are at greatest
risk
Contrast related side effects

17. Factors to Consider When Determining
Need of CT in Patients with Head Injury
Indications for urgent CT scan include:
Evidence of skull fracture—basal, depressed,
or open
Abnormal results of neurologic examination
Seizure
Vomiting >1 time

18. High-risk mechanism (e.g., ejection from vehicle;
pedestrian or cyclist versus automobile)
Decreasing GCS score or persistently decreased GCS
score of <15.

19. Indications for lower threshold for CT scan
include:
Age >60 yr
Persistent anterograde amnesia
Retrograde amnesia >30 min
Coagulopathy
Fall >5 stairs or >3 feet

20. Cont..
Intoxication (examination unreliable)
LOC >30 min
Mechanism and location of injury
Social factors (e.g., abusive situation at home,
language barriers preclude accurate history)

21. Magnetic Resonance Imaging

22. Advantages of MRI
Uses non ionizing radiation
Less invasive technique
Multiplanar capability
Excellent soft tissue contrast
Ability to depict flowing blood without the need of IV
contrast administration

23. Disadvantages of MRI
Cost
Limited Availability
Length of the examination time
Physiological motion artifacts
Acoustic noise

24. Contraindications of MRI
Ferrous object: Oxygen tanks, wheelchairs in the scan
room is extremely dangerous
Pts. who have electrically &/or magnetically activated
implants: Cardiac pace makers, Implanted
defibrillators
Pts. with intracranial aneurysm clips
Metal within the eye
Some decorative tattoos

25. Indications for CT, MRI Scanning
of Brain
General rules in brain imaging-
Acute neurological illness-
Start with CT
Sub acute/ Chronic
Start with MRI
MRI is the imaging study of choice in evaluating most
brain abnormalities
Head CT is the 1st
line modality for brain
emergency

26. Cont…
General rule in Spine imaging -
Bony spine-
CT, Conventional radiograph
Marrow replacing diseases-MRI
Intervertebral Disc-
MRI, CT Myelography
Contents : Spinal cord, nerve roots, ligaments-
MRI

27. Extraaxial Injury
Skull fracture
Epidural hematoma
Subdural hematoma
Subarachnoid hemorrhage

28. Skull Fracture
Not predictive of intracranial injury
Absence does not exclude intracranial injury
Types-Linear, depressed, basal, comminuted
Risk of brain injury increases with the depth of
depression

29. Skull x-ray findings-
Linear fracture-
• Lucent sharply defined
line without sclerotic
margin
Mimics-Vascular
groove , sutures

30. Depressed fracture –
• Increased or double
density on x-ray
• Best evaluated by
CT
• >5mm, elevation
indicated

31. Epidural Hematoma
Blood collection within potential space between skull
inner table & dura mater
75 % at the temporal region
Usually (99%)at the coup side
Majority have Skull fracture 85-95% ; In children
often absent
Mostly arterial bleed ,Due to laceration of the middle
meningeal artery or dural veins
Expands and present rapidly -Tense distension

32. Radiological signs
Biconvex with a sharply defined margin
Does not cross suture line unless there is
fracture/diastasis
Mass effect +/-brain herniation
Displacement of sinus, falx from the skull
Adjacent skull fracture

34. MANAGEMENT OF EDH
EDH > 30 cm3
should be evacuated.
EDH < 30 cm3
and <15 mm thickness and < 5 mm
midline shift and GCS >8 may be managed
nonoperatively with serial CT

35. SUBDURAL HEMATOMA
Occurs between the dura and arachnoid
Can cross the sutures but not the dural reflections
Due to disruption of the bridging cortical veins
hyperdense(acute), isodense(subacute)
Hypodense(chronic),

36. Radiological signs
Crescent shape
The most common locations are the frontal and
parietal convexities.
Countercoup
Unlike an EDH, its spread is not limited by suture
lines; it can spread over the whole convexity, but it
almost never crosses the midline
Mass effect +/-brain herniation
Skull fracture in < 50 %

37. SUBDURAL HEMATOMA

38. MANAGEMENT OF SDH
Acute SDH with thickness > 10 mm or midline shift >
5mm should be evacuated
Patient in coma with a decrease in GCS by >2 points
with a SDH should undergo surgical evacuation.

39. SUBARACHNOID HEMORRAGE
Can originate from direct vessel injury, contused cortex
or intraventricular hemorrhage.
In contrast to aneurysmal SAH, the blood is superficial in
the cortex and not present in the basal cisterns.
Usually focal (but diffuse from aneurysm)
In some instances, for example, if blood is found in the
sylvian fissure, a vascular study (CTA,DSA) is needed to
rule out an aneurysm rupture.
Can lead to communicating hydrocephalus

41. Intraventricular hemorrhage
Most commonly due to rupture of subependymal
vessels
Can occur from reflux of SAH or contiguous
extension of an intracerebral hemorrhage
Look for blood-cerebrospinal fluid level in occipital
horns

43. Intraaxial injury
Surface
contusion/laceration
Intraparenchymal
hematoma
White matter shearing
injury/diffuse axonal injury
Post-traumatic infarction
Brainstem injury

44. CONTUSION/LACERATIONS
Most common source of traumatic SAH
Contusion: must involve the superficial gray
matter
Laceration: contusion + tear of pia-arachnoid
Affects the crests of gyri
Hemorrhage present ½ cases and occur at right
angles to the cortical surface
Located near the irregular bony contours: poles of
frontal lobes, temporal lobes, inferior cerebellar
hemispheres

46. Intraparenchymal hematoma
Focal collections of blood that most commonly arise
from shear-strain injury to intraparenchymal vessels.
Usually located in the frontotemporal white matter or
basal ganglia
DDx: DAI, hemorrhagic contusion

48. DIFFUSE AXONAL INJURYDIFFUSE AXONAL INJURY
Rarely detected on CT ( 20% of DAI lesions are
hemorrhagic)
MRI: T1, T2, T2 GRE, DWI

49. DAI
Due to acceleration/deceleration to whtie matter +
hypoxia
Patients have severe LOC at impact
Grade 1: axonal damage in WM only -67%
Grade 2: WM + corpus callosum (posterior > anterior)
– 21%
Grade 3: WM + CC + brainstem

52. DTI

54. Traumatic cerebral infarct
Best diagnosed by: Restricted diffusion
Location-
 Most commonly occur in PCA vascular distribution,
 MCA, ACA, vertebrobasilar relatively common
 Other: Lenticulostriate, thalamoperforating;
cortical/subcortical; cerebellar

55. Traumatic cerebral infarct

57. SUBFALCIAL HERNIATION
Subfalcial: displacement of the cingulate gyrus under
the free edge of the falx along with the pericallosal
arteries.
Can lead to anterior cerebral artery infarction

58. DESCENDING HERNIATION

59. Herniation:
Ascending Transtentorial
Cranial shift of
vermis and parts of
superomedial
cerebellar
hemisphere through
tentorium incisura
 Compressed
superior cerebellar,
vermian cisterns and
forth ventricle

61. TONSILLAR HERNIATION
Inferior displacement of the cerebellar tonsils
through the foramen magnum
Can lead to posterior cerebellar artery infarction

63. EXTERNAL HERNIATION
Due to a defect in the
skull in combination
with elevated ICP
Venous obstruction
can occur at the
margins of the defect.

64. Conclusions
 CT = primary modality for head trauma, enough for
most parts
 Skull x-rays still used in penetrating trauma,
suspected child abuse
MRI to help predicting prognosis by detection of
subtle injuries i.e., contusion and DAI
Primary vs secondary lesion.
Often, secondary lesion more important

65. Conclusions
While checking the scan, make sure to think if the
patient needs CTA or other CTs (C-spine, facial
bones,
etc)
 Coup-contrecoup mechanism helps confirm acute
trauma nature and search for subtle lesions

66. Thank you
Thank you

67. References
Osborn Diagnostic Imaging Brain-2004
Bradley’s Neurology in Clinical Practice 6’th edition
2012
Slideshare.com
Radiopedia.com