Neuro Imaging

Question 1

what are the useful landmarks for imaging the brain

Answer 1

Lateral fissure
Central sulcus
Parietal-occipital fissure
Tentorium cerebelli

Question 2

what does the frontal lobe do

Answer 2

executing behaviour

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

Pre frontal cortex executive function;planning and executing complex behaviour

Question 3

what two cortex are in the frontal lobe

Answer 3

motor cortex

pre-frontal cortex

Question 4

what does the motor cortex contain

Answer 4

homunculus

Question 5

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

Answer 5

pre central gyrus – has the primary motor cortex

Post central gyrus – has the primary somatosensory cortex

Question 6

what does the parietal lobe do

Answer 6

Integration of sensory information

Primary somatosensory cortex post central gyrus and

Visuospatial processing
Complex sensory processing

Question 7

what are the black spaces in the Brian

Answer 7

CSF

Question 8

what happens if you have a lesions anteriorly

Answer 8

effects motor function

Question 9

what happens if you have a lesions posteriorly

Answer 9

effects sensory function

Question 10

what does the temporal lobe do

Answer 10

Auditory perception,

language, speech, memory, emotional response

Question 11

what does the occipital lobe do

Answer 11

Primary visual cortex

Question 12

describe an MRI photo of the optic pathway

Answer 12

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

Question 13

where is the corpus callosum

Answer 13

it sits on top of the lateral ventricle

Question 14

what does the cerebellum do

Answer 14

Motor control
Coordination
Posture/balance
Equilibrium

Question 15

what does the brainstem have in it

Answer 15

cranial nerve nuclei 3-12 and the white matter tracts

Question 16

what is the largest cranial nerve (not the longest)

Answer 16

trigeminal nerve

Question 17

what are the imaging options

Answer 17

Skull x ray
computerised tomography
MRI

Question 18

when is a Skull X ray used

Answer 18

Obsolete

Depressed skull # or penetrating injury only

Question 19

when is CT used

Answer 19

Mainstay in acute situation

Perfusion information

Question 20

When is MRI used

Answer 20

Occasionally acutely

Functional applicn/perfusion/spectroscopy

Question 21

How does CT image

Answer 21

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

Question 22

when is absorbed in a CT

Answer 22

bone is absorbed therefore it is white whereas air is not

Question 23

describe colours on a CT scan

Answer 23

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

Question 24

what scan can you see an haemorrhage on

Answer 24

CT

Question 25

what vessels does the subarachnoid space contain

Answer 25

Intracerebral

Question 26

how do you identify an anyerusm

Answer 26

use a CT angiography

Question 27

how does an angiography work

Answer 27

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

Question 28

what is stroke

Answer 28

Loss of arterial supply-

Question 29

what is ischaemia

Answer 29

irreversible infarction of brain tissue

Question 30

How do you treat aneurysms

Answer 30

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

Question 31

what are the advantages of CT

Answer 31

Excellent bone detail Good for blood + Ca + Limited soft tissue detail Vascular/perfusion-3D

Question 32

what are the disadvantages of CT

Answer 32

X-ray dose | Limited soft tissue resolution

Question 33

How does an MRI machine work

Answer 33

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

Question 34

what are the possible RF pulse sequences

Answer 34

T1 and T2

Question 35

H+ behave differently depending on...

Answer 35

H+ behave differently depending on their surroundings | =tissue characterisation

Question 36

what cannot go in the scanner

Answer 36

any magnetic materials

Question 37

what is the difference between T1 and T2

Answer 37

T2 weighted – CSF is white | T1 WEIGHTED – CSF is black

Question 38

what is T2 sensitivity to

Answer 38

T2 sensitive to pathology ``` tumours inflammation infection ischaemia scarring ``` High sensitivity Low specificity

Question 39

what is T1 sensitive to and describe T1

Answer 39

better anatomy less sensitive to pathology Sensitive to haemorrhage (not hyperacute) Identify fat Useful with contrast agent GADOLINIUM

Question 40

what does gadolinium IV do

Answer 40

Gadolinium-IV alters the T1 Relax time Does not cross an intact blood brain barrier Infection Infarction Tumour Inflammation- acute

Question 41

what can infect the brain

Answer 41

Bacterial meningitis usually not seen on imaging TB meningitis - severe inflammation / thickening of meninges around the basal cisterns

Question 42

what does DWI do

Answer 42

Shows areas of restricted water motion - Dying cells- cytotoxic oedema- infarction - Abscesses containing pus ( not TB)

Question 43

what does tractogrpahy - MR do

Answer 43

- follows the white matter tracts of the brain

Question 44

what are the advantages of MRI

Answer 44

- Excellent characterisation of lesions - Imaging in any plane (axial, coronal, sagittal) - No radiation

Question 45

what are the disadvantages of MRI

Answer 45

- Prolonged scanning time | - Strong magnetic field -1.5 T or 3T

Question 46

Compare CT to MRI

Answer 46

``` 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 ```