L12 Imaging of the Nervous System

Question 1

CT with contrast for spinal cord is called what?

Answer 1

CT myelogram

Question 2

where is contrast injected for a CT of the spinal cord?

Answer 2

lumbar cistern

Question 3

how much does air measure on the hounsfield scale?

Answer 3

-1000 HU

Question 4

how much does bone measure on the hounsfield scale?

Answer 4

1000 HU

Question 5

how much does water measure on the hounsfield scale?

Answer 5

0 HU

Question 6

how much does fat measure on the hounsfield scale?

Answer 6

-100 HU

Question 7

uses of CT?

Answer 7

bone fracture

acute bleeding

Question 8

patient has trauma to head. initially fine, but deteriorates in consciousness over hours. what is the classic condition?

Answer 8

epidural hematoma

Question 9

injury to the brain under the area of impact is called what? on opposite side?

Answer 9

coup and contre-coup

Question 10

in T1 MRI, what colour is CSF, WM, GM?

Answer 10

CSF dark
WM white
GM dark

Question 11

in T2 MRI, what colour is CSF, WM, GM?

Answer 11

CSF bright
WM dark
GM white

Question 12

gadolinium enhances which modality of MRI?

Answer 12

T1. rapidly shortens T1 relaxation.

Question 13

what shades are most pathologies in T1? T2?

Answer 13

dark in T1, bright in T2

Question 14

what does FLAIR stand for?

Answer 14

FLuid Attenuated Inversion Recovery

Question 15

how does hemoglobin change over time?

Answer 15

oxy-Hb
deoxy-Hb
met-Hb
hemosiderin

Question 16

which types of blood is MRI good for?

Answer 16

met-Hb and hemosiderin. MRI not good for acute blood.

Question 17

what is the area of hypoperfusion surrounding the ischemic core called?

Answer 17

penumbra

Question 18

what are signs of acute stroke?

Answer 18

loss of cortex/grey matter nuclei
swelling/loss of sulci
hyperdense MCA sign

Question 19

what is lacunar stroke?

Answer 19

a thrombus or embolus that blocks off one of the penetrating arteries from the circle of willis, cerebellar arteries, or basil artery

Question 20

when would you use MRI imaging in stroke?

Answer 20

small strokes
lacunar strokes
posterior fossa

Question 21

which modalities are useful for micro hemorrhages?

Answer 21

gradient echo (GRE)
susceptibility-weighted imaging (SWI)

Question 22

how does diffusion-weighted imaging (DWI) work?

Answer 22

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.

Question 23

what is an apparent diffusion coefficient (ADC) map?

Answer 23

a summation of the diffusion images in all 3 planes. infarct should be dark.

Question 24

how long is DWI and ADC good for post stroke?

Answer 24

good for the first 7-10 days. then membranes break down and water is not diffusion limited.

Question 25

what is FLAIR good for?

Answer 25

white matter lesions

Question 26

what is DWI/ADC good for?

Answer 26

acute stroke

Question 27

what is GRE/SWI good for?

Answer 27

chronic hemorrhage