CT brain interpretation: Difference between revisions

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==Mnemonic==
==Mnemonic==
Blood Can Be Very Bad
[[File:Brainlobes.png|thumb|Lobes of the brain.]]
#Blood
[[File:Cranial bones en.png|thumb|Bones of the cranium.]]
#Cisterns
[[File:Computed tomography of human brain - large.png|thumb|Example of a normal head CT with IV contrast.]]
#Brain
''Blood Can Be Very Bad''
#Ventricles
*Blood
#Bone
*Cisterns
*Brain
*Ventricles
*Bone


==Blood==
==Blood==
#Is blood present?
*Questions
#If so, where is it?
**Is blood present?
#If so, what effect is it having?
**If so, where is it?
 
**If so, what effect is it having?
Acute blood is bright white (once it clots)
*Physiology
Blood becomes isodense at 1wk (exact time depends on size of clot)
**Acute blood is bright white (once it clots)
Blood becomes hypodense at 2weeks (exact time depends on size of clot)
**Blood becomes isodense at 1wk (exact time depends on size of clot)
 
**Blood becomes hypodense at 2wks (exact time depends on size of clot)
Epidural (blood problem)
*Findings
Lens shaped
**[[Epidural hematoma]] (blood problem)
Does not cross sutures
***Lens shaped
Classically described w/ injury to middle meningeal artery
***Does not cross sutures
Low mortality if treated prior to unconsciousness (<20% morbidity/mortality)
***Classically described with injury to middle meningeal artery
 
***Low mortality if treated prior to unconsciousness (<20% morbidity/mortality)
Subdural (brain problem)
**[[SDH|Subdural]] (brain problem)
sickle shaped
***Sickle shaped
crosses sutures, but not midline
***Crosses sutures but not midline
Can have small Subdural but with major shift (2/2 brain injury/oozing/swelling)
***Marker for severe head injury (mortality approaches 80%)
Marker for severe head injury (mortality approaches 80%)
****Small amount of bleed can be associated with major shift (secondary to brain injury/oozing)
-Chronic subdural usually slow venous bleed and well tolerated
**[[SAH]]
 
***Blood in the cisterns/cortical gyral surface/interhemispheric fissure
SAH
****Suprasellar cistern is first place see SAH (location adjacent to circle of willis)
*Blood in the cisterns/cortical gyral surface
***Aneurysm: 80%
*Aneurysm: 80%
***[[AVM]]: 5%
AVM: 5%
**Intraventricular/Intraparenchymal Hemorrhage
 
***Typically obvious findings
*May see in interhemispheric fissure also
***Unimportant if intraventricular ruptured into parenchyma or vice-versa
 
*Suprasellar cistern is first place see SAH (circle of willis)
 
=========
Intraventricular/intraparenchymal hemorrhage
Not typically subtle
Doesn't matter if intraventricula rruptured into parenchyma or vice-versa


==Cisterns==
==Cisterns==
4 key cisterns:
*4 key cisterns:
#Circummesencephalic
**Circummesencephalic
#Suprasellar
***First cistern to show increased ICP (squished shut)
#Quadrigeminal
**Suprasellar
#Sylvian
**Quadrigeminal
 
***"W" shaped
2 questions:
***Second cistern to show increased ICP
#Is there blood?
**Sylvian
#Are the cisterns open?
***May see isloated distal MCA bleed
*2 questions:
**Is there blood?
**Are the cisterns open?


==Brain==
==Brain==
#Compare side to side
*Compare side to side
#Look for grey-white differentiation
*Look for grey-white differentiation
##Grey is denser so appears lighter on CT
**Grey is denser so appears lighter on CT
#Look at gyral pattern all the way around (gyri effacement indicator of incr ICP)
*Look at gyral pattern all the way around (gyri effacement indicator of increased ICP)
 
*Findings
#Tumor: may see increased hypodensity (edema)
**[[brain tumor|Tumor]]
##80% visisble w/o contrast
***May see increased hypodensity ([[cerebral edema in brain cancer|edema]])
Atrophy  
***80% visible without contrast
Abscess
**Atrophy  
 
**[[brain abscess|Abscess]]
(contrast lights at areas of breakdown in BBB)
**Hemorrhagic contusion
 
**Mass effect
Hemorrhagic contusion (deceleration injury from brain banging into frontal fossa)
**[[Stroke]]
#Hyperdensities
**Intracranial air ([[skull fracture]])
 
**Hyperdense middle cerebral artery or basilar artery sign
Mass effect
***Suggests thrombosis of vessel
Stroke
**Suggestive of [[Cerebral venous thrombosis]] :
Intracranial air (skull fx)
***Empty delta sign: dense triangle in superior sagittal sinus
***Cord sign: hyperattenuated, homogeneous linear or round foci in cerebral sinus <ref>Ram K. P. Vijay. "The Cord Sign."Radiology. 2006; 240:299-300.</ref>
***Vein Sign: hypoattenuated foci in the deep vein  <ref>Linn J, Pfefferkorn T. "Noncontrast CT in Deep Cerebral Venous Thrombosis and Sinus Thrombosis: Comparison of Its Diagnostic Value for Both Entities."AJNR Am J Neuroradiology. 2010; 30: 728-735. </ref>


==Ventricles==
==Ventricles==
#Check all 4 for size and for hemorrhage
*Check all 4 for size and for hemorrhage
##Size: Differentiate between hydrocephalus from incr pressure versus from atrophy (ex-vacuo)
**Temporal tips (comma-shaped) of lateral ventricle first place to show hydrocephalus
###Are the gyri effaced?
**If enlarged must differentiate between [[hydrocephalus]] from increased pressure versus atrophy:
 
***Are the gyri effaced? If yes suggestive of increased pressure
If ventricles enlarged --> hydrocephalus


==Bone==
==Bone==
#Petrous ridges for skull base fx
*Inspect petrous ridges for [[basilar skull fracture|skull base fracture]]
#Look at mastoid air cells full of fluid (blood) for indirect e/o fracture
*Look at mastoid air cells full of fluid (blood) for indirect evidence of fracture
 
 
If no blood is seen, all 4 cisterns are present and open and no blood, the brain is symmetric w/ normal gray-white differentiation, gyral pattern is normal, the ventricles are symmetric without dilation and no blood, and there is no fx, then there is no emergent dx from the CT scan
 
 
 
*Circummescephalic cistern is first one that shows incr ICP (squished shut)
*Quadrigeminal cistern ("W" shaped) is second one that shows incr ICP
 
*Temporal tips (comma-shaped) of lateral ventricle is first place where see hydrocephalus (incr intraventricular pressure)
**1/5 pts w/ SAH hemorrhage develop hydrocephalus
 
----can view suprasellar cistern and temporal tips all in one view
 
Sylvian cistern is where distal MCA bleeds sometimes are seen


==Examples==
<gallery mode="packed">
File:Intracerebral heamorrage.jpg|[[Hemorrhagic stroke]] (spontaneous intracranial hemorrhage)
File:Epidural Hematoma.jpg|[[Epidural hemorrhage]]
File:Subduralandherniation.png|[[Subdural hemorrhage]]
File:SubarachnoidP.png|[[Subarachnoid hemorrhage]]
File:Hydrocephalus (cropped).jpg|[[Hydrocephalus]]
File:PMC4857327 10.1177 2050313X15591314-fig3.png|[[Brain abscess]]
File:StrokeMCA overlay.png|[[Ischemic stroke]]
</gallery>


# Brain density-grey vs white matter
==See Also==
# midline shift
*[[Head CT (Clinical Decision Rules)]]
# Subarach space-syl fissure - look for sulci
*[[CT Before Lumbar Puncture]]
# vent system - look at temp horns
*[[Intracerebral Hemorrhage (ICH)]]
# Corner shots - eyes / bones
*[[X-ray interpretation (main)]]


==Source==
==References==
Blood Can Be Very Bad: CT Interpretation Course Guide
*Blood Can Be Very Bad: CT Interpretation Course Guide
*www.uic.edu/com/ferne/pdf/acep2005_spring/perron_acep2005_spring_bcbvb_course.pdf
*www.uic.edu/com/ferne/pdf/acep2005_spring/perron_acep2005_spring_bcbvb_course.pdf
<references/>


[[Category:Neuro]]
[[Category:Neurology]]
[[Category:Rads]]
[[Category:Radiology]]

Latest revision as of 22:29, 25 January 2023

Mnemonic

Lobes of the brain.
Bones of the cranium.
Example of a normal head CT with IV contrast.

Blood Can Be Very Bad

  • Blood
  • Cisterns
  • Brain
  • Ventricles
  • Bone

Blood

  • Questions
    • Is blood present?
    • If so, where is it?
    • If so, what effect is it having?
  • Physiology
    • Acute blood is bright white (once it clots)
    • Blood becomes isodense at 1wk (exact time depends on size of clot)
    • Blood becomes hypodense at 2wks (exact time depends on size of clot)
  • Findings
    • Epidural hematoma (blood problem)
      • Lens shaped
      • Does not cross sutures
      • Classically described with injury to middle meningeal artery
      • Low mortality if treated prior to unconsciousness (<20% morbidity/mortality)
    • Subdural (brain problem)
      • Sickle shaped
      • Crosses sutures but not midline
      • Marker for severe head injury (mortality approaches 80%)
        • Small amount of bleed can be associated with major shift (secondary to brain injury/oozing)
    • SAH
      • Blood in the cisterns/cortical gyral surface/interhemispheric fissure
        • Suprasellar cistern is first place see SAH (location adjacent to circle of willis)
      • Aneurysm: 80%
      • AVM: 5%
    • Intraventricular/Intraparenchymal Hemorrhage
      • Typically obvious findings
      • Unimportant if intraventricular ruptured into parenchyma or vice-versa

Cisterns

  • 4 key cisterns:
    • Circummesencephalic
      • First cistern to show increased ICP (squished shut)
    • Suprasellar
    • Quadrigeminal
      • "W" shaped
      • Second cistern to show increased ICP
    • Sylvian
      • May see isloated distal MCA bleed
  • 2 questions:
    • Is there blood?
    • Are the cisterns open?

Brain

  • Compare side to side
  • Look for grey-white differentiation
    • Grey is denser so appears lighter on CT
  • Look at gyral pattern all the way around (gyri effacement indicator of increased ICP)
  • Findings
    • Tumor
      • May see increased hypodensity (edema)
      • 80% visible without contrast
    • Atrophy
    • Abscess
    • Hemorrhagic contusion
    • Mass effect
    • Stroke
    • Intracranial air (skull fracture)
    • Hyperdense middle cerebral artery or basilar artery sign
      • Suggests thrombosis of vessel
    • Suggestive of Cerebral venous thrombosis :
      • Empty delta sign: dense triangle in superior sagittal sinus
      • Cord sign: hyperattenuated, homogeneous linear or round foci in cerebral sinus [1]
      • Vein Sign: hypoattenuated foci in the deep vein [2]

Ventricles

  • Check all 4 for size and for hemorrhage
    • Temporal tips (comma-shaped) of lateral ventricle first place to show hydrocephalus
    • If enlarged must differentiate between hydrocephalus from increased pressure versus atrophy:
      • Are the gyri effaced? If yes suggestive of increased pressure

Bone

  • Inspect petrous ridges for skull base fracture
  • Look at mastoid air cells full of fluid (blood) for indirect evidence of fracture

Examples

See Also

References

  • Blood Can Be Very Bad: CT Interpretation Course Guide
  • www.uic.edu/com/ferne/pdf/acep2005_spring/perron_acep2005_spring_bcbvb_course.pdf
  1. ↑ Ram K. P. Vijay. "The Cord Sign."Radiology. 2006; 240:299-300.
  2. ↑ Linn J, Pfefferkorn T. "Noncontrast CT in Deep Cerebral Venous Thrombosis and Sinus Thrombosis: Comparison of Its Diagnostic Value for Both Entities."AJNR Am J Neuroradiology. 2010; 30: 728-735.
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