Head Flashcards
(29 cards)
What are indications for a head CT scan
Stroke, TIA, hemorrhage, trauma, AVM, tumors, aneurysm, more…
What is the patient position for Head CT
Supine, Head in holder, immobilized head. OML, or even more preferred, SOML parallell with gantry (chin tucked down)
Why would having the OML or SOML be beneficial to the patient when scanning
It reduces the radiation exposure to the lens of the eye
What type of scan is routine brain according to romans
Axial (step and shoot)
What is included in a scan of the had
Skull base: Foramen magnum through petrous ridges
Temporal bones: just below mastoid process to just above petrous ridges
Sella: below sellar floor through dorsum sellae
Why are beam hardening artifacts often seen in images of posterior fossa
Because the skull base is so dense
How might artifacts be reduced for skull artifacts
thinner slices
Is there CM for head CT routinely
no
When might CM be used for head CT
Infections, neoplasms
At what rate may someone hand inject CM for a head CT
~1ml/s
What are the window settings for slices in post fossa
Soft tissue brain 160ww/40wl
What are the window settings for slices above post fossa to vertex
Soft tissue brain 100ww/30wl
What bone window settings
2500ww/400wl
What blood window settings
200ww/60wl
What is the relationship between brain density and edema after a stroke
As edema progresses brain density will decrease proportionately
How much increase of water will result from a stroke after 6 hours
6% increase in water
How many Hounsfield units will decrease after one hour post stroke
7-8HU
What does ICH stand for
Intracranial Hemorrhage
Where does density loss start in the head after an ICH
Density loss starts at the periphery/outskirts of the hematoma
When does ICH begin to present as hyperdense
1-3 days post stroke
When does the center become hyperdense and the concentric tissue become hyper/hypodense
4-10 days
When will the center become isodense surrounded with hypodense tissue
11 days to 6 months
When does the tissue become hypodense to normal
after approximately 6 months
What is t-PA
Tissue plasminogen activator.
It is a pharmacologic treatment for acute ISCHEMIC stroke
