CT brain interpretation
(Redirected from Head CT)
Mnemonic
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%
- Blood in the cisterns/cortical gyral surface/interhemispheric fissure
- Intraventricular/Intraparenchymal Hemorrhage
- Typically obvious findings
- Unimportant if intraventricular ruptured into parenchyma or vice-versa
- Epidural hematoma (blood problem)
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
- Circummesencephalic
- 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 :
- Tumor
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
Hemorrhagic stroke (spontaneous intracranial hemorrhage)
See Also
- Head CT (Clinical Decision Rules)
- CT Before Lumbar Puncture
- Intracerebral Hemorrhage (ICH)
- X-ray interpretation (main)
References
- Blood Can Be Very Bad: CT Interpretation Course Guide
- www.uic.edu/com/ferne/pdf/acep2005_spring/perron_acep2005_spring_bcbvb_course.pdf