CT brain interpretation

Mnemonic

Blood Can Be Very Bad

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 w/ 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 w/ major shift (2/2 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

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 incr ICP)
Findings
- Tumor
  - May see increased hypodensity (edema)
  - 80% visisble w/o contrast
- Atrophy
- Abscess
- Hemorrhagic contusion
- Mass effect
- Stroke
- Intracranial air (skull fx)
- Hyperdense middle cerebral artery or basilar artery sign
  - Suggests thrombosis of vessel

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 incr pressure versus atrophy:
  - Are the gyri effaced? If yes suggestive of incr pressure

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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