CT head Flashcards
What are the indications for head CT?
(12 things)
- stroke
- TIA
- Hemorrhage
- Trauma
- Acute neuro changes
- Tumors
- AVM
- Thrombosis
- Aneurysm
- Headache / seizures
- mass / lesion / hearing loss
- unknown/surprises (parasites etc..)
Why is the SOML the one we align instead of OML?
- avoids radiation exposure to eye lens
Gantry tilt and patient position will affect images in which plane?
- Axial plane
Dense skull base causes beam hardening artifacts, what are the 2 ways to reduce these artifacts?
- thinner slices
- increase kV
When are helical scans taken for the head?
- CTA’s
Routinely, no contrast is used, what is demonstrated?
- structural images of the brain and base of skull
Enhanced CT head is done for:
(2 main things)
- infections
- neoplasms
- or MRI if not contraindicated
What is the flow rate for CT head?
- 1mL/s (hand inject possible)
What are the 4 window settings for brain?
- soft tissue in posterior fossa: 160ww/40wl
- soft tissue above post. fossa to vertex: 100ww/30wl
- bone: 2500ww/400wl
- blood: 200ww/60wl
What accounts for 80% of almost all strokes?
- Ischemic strokes
What does stroke do?
(4 things)
- Edema progresses
- brain density decreases a lot
- within 1 hour, 3% increase in intraparenchymal water occurs
- 7-8 HU decrease in brain density
What is CVA?
- cerebral vascular accident
- aka stroke
How will the brain appear 3 hours after onset of symptoms? 1 day? 3 months?
- looks normal
- some loss of grey-white mater differentiation
- clear area of hypodensity
What is an ICH stroke?
- intracranial hemorrhage stroke
Generally, how will ICH appear?
(4 things)
- 1-3 days: hyperdense
- 4-10 days: hyperdense center with concentric hyper/hypodense tissue
- 11days-6months: Isodense center with hypodense tissue around it
- > 6 months: hypodense to normal brain tissue
what is t-PA?
tissue plasminogen activator
what does t-PA do?
- treats acute ischemic stroke
- must be given within 3 hours of first signs of stroke
What is the contraindications for t-PA
- if it was NOT an ischemic stroke and was instead and intracranial hemorrhage stroke
What is routinely performed to differnitate ischemic or hemorrhagic strokes
- noncontrast CT
What is the use of CM for strokes?
(2 things)
- assess the state of cerebral circulation and tissue
- secondly, assess the underlying disease
How does CT brain perfusion studies provide additional info?
- allowing quantitative and qualitative evaluation of cerebral perfusion
What are the 3 types of cerebral aneurysems?
- fusiform
- berry
- saccular
