Neuro Imaging Flashcards

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1
Q

what are the useful landmarks for imaging the brain

A

Lateral fissure
Central sulcus
Parietal-occipital fissure
Tentorium cerebelli

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2
Q

what does the frontal lobe do

A

executing behaviour

Motor cortex- direct control of voluntary muscles via the brainstem and cord

Pre frontal cortex executive function;planning and executing complex behaviour

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3
Q

what two cortex are in the frontal lobe

A

motor cortex

pre-frontal cortex

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4
Q

what does the motor cortex contain

A

homunculus

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5
Q

what’s the difference between pre-central gyrus and post central gyrus

A

pre central gyrus – has the primary motor cortex

Post central gyrus – has the primary somatosensory cortex

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6
Q

what does the parietal lobe do

A

Integration of sensory information

Primary somatosensory cortex post central gyrus and

Visuospatial processing
Complex sensory processing

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7
Q

what are the black spaces in the Brian

A

CSF

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8
Q

what happens if you have a lesions anteriorly

A

effects motor function

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9
Q

what happens if you have a lesions posteriorly

A

effects sensory function

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10
Q

what does the temporal lobe do

A

Auditory perception,

language, speech, memory, emotional response

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11
Q

what does the occipital lobe do

A

Primary visual cortex

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12
Q

describe an MRI photo of the optic pathway

A

MRI scan through the orbits

Can see the globes and lens – lens is dark - doesn’t contain so much free water

Coming of the back of the globe you can see the optic nerev can see the CSF nerve sheath around it

Goes through a bony canal

Can see optic chiasm

Can see the optic radiations that it gives of

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13
Q

where is the corpus callosum

A

it sits on top of the lateral ventricle

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14
Q

what does the cerebellum do

A

Motor control
Coordination
Posture/balance
Equilibrium

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15
Q

what does the brainstem have in it

A

cranial nerve nuclei 3-12 and the white matter tracts

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16
Q

what is the largest cranial nerve (not the longest)

A

trigeminal nerve

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17
Q

what are the imaging options

A

Skull x ray
computerised tomography
MRI

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18
Q

when is a Skull X ray used

A

Obsolete

Depressed skull # or penetrating injury only

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19
Q

when is CT used

A

Mainstay in acute situation

Perfusion information

20
Q

When is MRI used

A

Occasionally acutely

Functional applicn/perfusion/spectroscopy

21
Q

How does CT image

A

Whole body t 20-30 seconds
Produces over 1000 slices in this time frame
Can image soft tissue

22
Q

when is absorbed in a CT

A

bone is absorbed therefore it is white whereas air is not

23
Q

describe colours on a CT scan

A

Air
- 1000
very black

Fat -100 black

Water 0 dark grey

Brain +40 grey

Blood +90 white

I Contrast +100 white

Bone +1000 very white

24
Q

what scan can you see an haemorrhage on

A

CT

25
Q

what vessels does the subarachnoid space contain

A

Intracerebral

26
Q

how do you identify an anyerusm

A

use a CT angiography

27
Q

how does an angiography work

A

Feel the blood vessels with contrast medium that contains iodine so they show up on the CT scan
100mls of contrast

Wait for it to go up the brain into the aorta and carotid artery

Gets a picture of the arteries and not the veins

Get a picture of the circle of willis

Anneruysms form where the areas branch of

28
Q

what is stroke

A

Loss of arterial supply-

29
Q

what is ischaemia

A

irreversible infarction of brain tissue

30
Q

How do you treat aneurysms

A

Treat aneurysms – clip or coil - put a femoral cather in the groin and then a thin wire and then pack the aneryrms with coils until the whole thing is packed with coils and then there is no blood flow to that area

31
Q

what are the advantages of CT

A

Excellent bone detail

Good for blood + Ca +

Limited soft tissue detail

Vascular/perfusion-3D

32
Q

what are the disadvantages of CT

A

X-ray dose

Limited soft tissue resolution

33
Q

How does an MRI machine work

A

1.5 Tesla static magnetic field

Apply an RF pulse via a coil - all H+ spin, stop the RF pulse
- Relaxation of H+

Apply magnetic gradients allows for spatial resolution

34
Q

what are the possible RF pulse sequences

A

T1 and T2

35
Q

H+ behave differently depending on…

A

H+ behave differently depending on their surroundings

=tissue characterisation

36
Q

what cannot go in the scanner

A

any magnetic materials

37
Q

what is the difference between T1 and T2

A

T2 weighted – CSF is white

T1 WEIGHTED – CSF is black

38
Q

what is T2 sensitivity to

A

T2 sensitive to pathology

tumours
inflammation
infection
ischaemia
scarring 

High sensitivity
Low specificity

39
Q

what is T1 sensitive to and describe T1

A

better anatomy
less sensitive to pathology

Sensitive to haemorrhage
(not hyperacute)

Identify fat

Useful with contrast agent
GADOLINIUM

40
Q

what does gadolinium IV do

A

Gadolinium-IV alters the T1
Relax time

Does not cross an intact
blood brain barrier

Infection
Infarction
Tumour
Inflammation- acute

41
Q

what can infect the brain

A

Bacterial meningitis usually not seen on imaging

TB meningitis - severe inflammation / thickening of meninges around the basal cisterns

42
Q

what does DWI do

A

Shows areas of restricted water motion

  • Dying cells- cytotoxic oedema- infarction
  • Abscesses containing pus ( not TB)
43
Q

what does tractogrpahy - MR do

A
  • follows the white matter tracts of the brain
44
Q

what are the advantages of MRI

A
  • Excellent characterisation of lesions
  • Imaging in any plane (axial, coronal, sagittal)
  • No radiation
45
Q

what are the disadvantages of MRI

A
  • Prolonged scanning time

- Strong magnetic field -1.5 T or 3T

46
Q

Compare CT to MRI

A
CT
Quick
Easily  available
1st line
Acute trauma & stroke and blood
Radiation
Perfusion  
MRI
Time consuming
Multiplanar
Resolution better
Strong Magnetic field
No radiation
Functional
Spectroscopic