CT brain interpretation: Difference between revisions

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==Blood==
==Blood==
===Questions===
#Is blood present?
#Is blood present?
#If so, where is it?
#If so, where is it?
#If so, what effect is it having?
#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 Hematom (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 w/ injury to middle meningeal artery
 
##Low mortality if treated prior to unconsciousness (<20% morbidity/mortality)
Subdural (brain problem)
#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 w/ major shift (2/2 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 incr ICP (squished shut)
#Quadrigeminal
##Suprasellar
#Sylvian
##Quadrigeminal
 
###"W" shaped
2 questions:
###Second cistern to show incr 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==
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##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 incr ICP)
 
#Findings
#Tumor: may see increased hypodensity (edema)
##Tumor
##80% visisble w/o contrast
###May see increased hypodensity (edema)
Atrophy  
###80% visisble w/o contrast
Abscess
##Atrophy  
 
##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 fx)
 
Mass effect
Stroke
Intracranial air (skull fx)


==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 incr pressure versus atrophy:
 
###Are the gyri effaced? If yes suggestive of incr pressure
If ventricles enlarged --> hydrocephalus


==Bone==
==Bone==
#Petrous ridges for skull base fx
#Inspect petrous ridges for skull base fx
#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 e/o fracture


 
==Overall==
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
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
# Brain density-grey vs white matter
# midline shift
# Subarach space-syl fissure - look for sulci
# vent system - look at temp horns
# Corner shots - eyes / bones


==Source==
==Source==

Revision as of 08:27, 29 September 2011

Mnemonic

Blood Can Be Very Bad

  1. Blood
  2. Cisterns
  3. Brain
  4. Ventricles
  5. Bone

Blood

Questions

  1. Is blood present?
  2. If so, where is it?
  3. If so, what effect is it having?

Physiology

  1. Acute blood is bright white (once it clots)
  2. Blood becomes isodense at 1wk (exact time depends on size of clot)
  3. Blood becomes hypodense at 2wks (exact time depends on size of clot)

Findings

  1. Epidural Hematom (blood problem)
    1. Lens shaped
    2. Does not cross sutures
    3. Classically described w/ injury to middle meningeal artery
    4. Low mortality if treated prior to unconsciousness (<20% morbidity/mortality)
  2. Subdural (brain problem)
    1. Sickle shaped
    2. Crosses sutures but not midline
    3. Marker for severe head injury (mortality approaches 80%)
      1. Small amount of bleed can be associated w/ major shift (2/2 brain injury/oozing)
  3. SAH
    1. Blood in the cisterns/cortical gyral surface/interhemispheric fissure
      1. Suprasellar cistern is first place see SAH (location adjacent to circle of willis)
    2. Aneurysm: 80%
    3. AVM: 5%
  4. Intraventricular/Intraparenchymal Hemorrhage
    1. Typically obvious findings
    2. Unimportant if intraventricular ruptured into parenchyma or vice-versa

Cisterns

  1. 4 key cisterns:
    1. Circummesencephalic
      1. First cistern to show incr ICP (squished shut)
    2. Suprasellar
    3. Quadrigeminal
      1. "W" shaped
      2. Second cistern to show incr ICP
    4. Sylvian
      1. May see isloated distal MCA bleed
  2. 2 questions:
    1. Is there blood?
    2. Are the cisterns open?

Brain

  1. Compare side to side
  2. Look for grey-white differentiation
    1. Grey is denser so appears lighter on CT
  3. Look at gyral pattern all the way around (gyri effacement indicator of incr ICP)
  4. Findings
    1. Tumor
      1. May see increased hypodensity (edema)
      2. 80% visisble w/o contrast
    2. Atrophy
    3. Abscess
    4. Hemorrhagic contusion
    5. Mass effect
    6. Stroke
    7. Intracranial air (skull fx)

Ventricles

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

Bone

  1. Inspect petrous ridges for skull base fx
  2. Look at mastoid air cells full of fluid (blood) for indirect e/o fracture

Overall

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

Source

Blood Can Be Very Bad: CT Interpretation Course Guide

  • www.uic.edu/com/ferne/pdf/acep2005_spring/perron_acep2005_spring_bcbvb_course.pdf
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