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Hot topics in Neurology and Psychiatry > Research MRI and networks > Flashcards

Research MRI and networks Flashcards

1
Q

T1 can show

A

gadolineum (recent lesions), sever destruction

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2
Q

T2 can show

A

lesions in MS, water, the loss of membranes

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3
Q

what is FLAIR?

A

a T2 with suppressed CSF. therefore the contrast is easier to see.

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4
Q

what is DIR

A

FLAIR with white matter suppression, even more contrast.

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5
Q

zijn deze technieken qualitative or quantitative

A

qualitative -> is there a lesion or not? zeggen niks over de severity of lesions (quantitative)

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6
Q

main T… for tumors?

A

T1

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7
Q

main T.. for atrophy?

A

T1

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8
Q

difference imaging in clinic and research

A

in the clinic you need to make fast images, in research detail is important

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9
Q

axal is… radial is…

A

lang, korte lijn

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10
Q

wat meet je met een DTI (of diffused tensor imaging/diffused weighted imaging)

A

how the free weighted water moves

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11
Q

bij MS en DTI:

A

bij MS is het myeline op bepaalde plekken weg. hierdoor kan het water meer freely bewegen. de patient heeft dan een lagere fractional anisotrophy.

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12
Q

waardoor increased axial diffusion?

A

bc of atrophy -> more extracellular fluids and then higher axial diffusion

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13
Q

increased radial diffusion because of…

A

demyelination. that leads to anisotrophic diffusion (does not move in the same direction)

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14
Q

What can you measure with DTI?

A

subtle damage, quantitative in research

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15
Q

what is structural connectivity

A

to quantify the number of axons between two brain regions.

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16
Q

hoe kan je structural connectivity krijgen

A

dmv een DTI

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17
Q

deterministic tractography

A

you measure all bundles from one axon, and then show the mean direction in which they go. you show the strongest pathway from one region to another (but then you also miss a lot).

18
Q

probabilistic tractography

A

you assign a probability that it will go in that way. you get more different pathways, and keep that information (bij deterministic vallen de zwakke pathways weg)

19
Q

BOLD response

A

more neuronal activity is more metabolism is more oxygen use

20
Q

wat voor research kan je doen met een functional mri

A

kijken naar plaatjes waarvan je dingen herkent. dan moet je ook plaatjes laten zien van andere aspecten, zodat alleen de recognition overblijft.

21
Q

functional connectivity

A

kijken of brain regions met elkaar in verbinding staan. -> correlation

22
Q

difference in centrality dynamics patients vs healthy

A

healthy kan goed switchen tussen stages of focus and default mode. bij cognitive impairment zijn deze tegelijkertijd aanwezig.

23
Q

andere naam voor connection

A

edges

24
Q

what kind of distribution does the human brain have?

A

power law distribution -> many nodes with few connections, few nodes with many connections

25
Q

weighted graph

A

number of connections, meer connections is een dikkere lijn (DTI!)

26
Q

wat is beter: lange of korte pathlenght?

A

korte

27
Q

clustering coefficient

A
  • how many of my friends are friends? dus hoeveel neighbours zijn ook connected met elkaar?
  • aantal connected neighbours / aantal neighbours
28
Q

small world network

A

een balans tussen korte pathways maar wel clusters

29
Q

wat is een hub?

A

heeft een high degree of connections

30
Q

twee verschillende soorten hubs

A
  • een connector hub connects zijn eigen cluster aan een andere cluster.
  • een provincial hub zit midden in een cluster, en is dus aan veel binnen zijn eigen cluster verbonden
31
Q

minimum spanning tree

A

the path of all higher connected hubs, that can reach all nodes

32
Q

bij MS patients is de minimum spanning tree..

A

een soort lijn, elke node is maar connected aan een andere node

33
Q

wat is hier dan het verschil?

A

de nodes zijn niet veranderd!!! maar de connections tussen de nodes wel!

34
Q

rich club

A

highly connected nodes that are also connected to each other.

35
Q

what 4 factors determine centrality?

A
  • degree connectivity -> how many connections
  • closeness centrality -> distance to all other nodes
  • betweenness centrality -> number of shortest paths that go throught the node
  • degree prestige -> how many high-quality connections?
36
Q

what is happening with the default mode network in cognitive impairment

A

more present, centrality of the default network increases.

37
Q

what happens in MS with the connections?

A

less connections, therefore simpler. it takes longer to get the information where it needs to be.

38
Q

what does DTI measure? and what kind of connectivity do you therefore measure?

A

NUMBER OF CONNECTIONS, structural connectivity

39
Q

what does functional connectivity measure

A

the degree of similarity between two signals

40
Q

small world measures

A

pathlength and connectivity

41
Q

static connectivity

A

connectivity across entire scan

42
Q

dynamic connectivity

A

connectivity varies over time

Hot topics in Neurology and Psychiatry (50 decks)

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