L12 Imaging of the Nervous System Flashcards
CT with contrast for spinal cord is called what?
CT myelogram
where is contrast injected for a CT of the spinal cord?
lumbar cistern
how much does air measure on the hounsfield scale?
-1000 HU
how much does bone measure on the hounsfield scale?
1000 HU
how much does water measure on the hounsfield scale?
0 HU
how much does fat measure on the hounsfield scale?
-100 HU
uses of CT?
bone fracture
acute bleeding
patient has trauma to head. initially fine, but deteriorates in consciousness over hours. what is the classic condition?
epidural hematoma
injury to the brain under the area of impact is called what? on opposite side?
coup and contre-coup
in T1 MRI, what colour is CSF, WM, GM?
CSF dark
WM white
GM dark
in T2 MRI, what colour is CSF, WM, GM?
CSF bright
WM dark
GM white
gadolinium enhances which modality of MRI?
T1. rapidly shortens T1 relaxation.
what shades are most pathologies in T1? T2?
dark in T1, bright in T2
what does FLAIR stand for?
FLuid Attenuated Inversion Recovery
how does hemoglobin change over time?
oxy-Hb
deoxy-Hb
met-Hb
hemosiderin
which types of blood is MRI good for?
met-Hb and hemosiderin. MRI not good for acute blood.
what is the area of hypoperfusion surrounding the ischemic core called?
penumbra
what are signs of acute stroke?
loss of cortex/grey matter nuclei
swelling/loss of sulci
hyperdense MCA sign
what is lacunar stroke?
a thrombus or embolus that blocks off one of the penetrating arteries from the circle of willis, cerebellar arteries, or basil artery
when would you use MRI imaging in stroke?
small strokes
lacunar strokes
posterior fossa
which modalities are useful for micro hemorrhages?
gradient echo (GRE) susceptibility-weighted imaging (SWI)
how does diffusion-weighted imaging (DWI) work?
in stroke, no glucose means no Na movement, means no water movement. DWI takes advantage of stagnant water here to do imaging. diffusion weighting usually between 0-1000 units.
what is an apparent diffusion coefficient (ADC) map?
a summation of the diffusion images in all 3 planes. infarct should be dark.
how long is DWI and ADC good for post stroke?
good for the first 7-10 days. then membranes break down and water is not diffusion limited.
