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brain scans Flashcards

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1
Q

what does PET stand for?

A

Positron Emission Tomography

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2
Q

what does a PET scan look for?

A

Show us ACTIVITY
– which parts are most/least active.
- we know this from different colours that show up (warm colours=more activity)

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3
Q

what does it look like?

A

Doughnut shaped scanner

that is put around the head.

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4
Q

how does the brain function?

A

by the use of glucose and water

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5
Q

what is a tracer?

A

Tracers are radioactive versions of chemicals used up during
brain activity, such as glucose or water, e.g., FDG
(fluorodeoxyglucose)

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6
Q

what is injected into the patient during a PET scan?

A

• A tracer is injected into the bloodstream.

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7
Q

how long does a tracer take to get to the brain?

A

The tracer reaches the brain about 1 minute after being

injected.

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8
Q

what does the brain cell do once the tracer is injected in a PET scan?

A

The brain cells start to uptake the oxygen in the

water or the glucose and then the tracer begins to decay

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9
Q

how long does it take for the tracer to decay in a PET scan?

A

10-15 mins

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10
Q

what does the tracer release as it decays during a PET scan?

A

. As it decays, it releases
minute amounts of radioactivity (initially in the form of
positrons).

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11
Q

how are the most active area’s identified during a PET scan?

A

Most active areas use most glucose and leave behind the
most radiation (the positively charged particles called
positrons). Positrons give signals that are picked up by
recordings.

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12
Q

what is the radioactivity in the form of in a PET scan?

A

The radioactivity is in the form of gamma rays
which are produced when the positrons collide with
electrons.

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13
Q

what does FMRI stand for?

A

functional Magnetic Resonance Imaging

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14
Q

what is the idea behind FMRI?

A
  • The idea is that brain activity is associated with blood flow in the brain.
  • this activity is used to gather the
    information by the scanner to produce a picture
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15
Q

What does FMRI involve the patient to do, what does it look like?

A

Involves having your head placed in a large, very powerful electromagnet.

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16
Q

what occurs inside the magnetic field during FMRI?

A

Inside the magnetic field, the nuclei within hydrogen

molecules in water align themselves with the direction of the magnetic field.

17
Q

what happens when activity increases in the brain during FMRI?

A

blood flow increases in the active areas to keep up with the demand for oxygen.

18
Q

how is the oxygen carried during FMRI ?

A

The oxygen is carried to the neurons in haemoglobin within red blood cells.

19
Q

in FMRI what allows them to detect changes and create an image?

A
  • When haemoglobin carries oxygen, it repels a magnetic field
  • when haemoglobin becomes deoxygenated it will follow the direction of the magnetic field
  • it is these changes the scanner will
    detect to create an image.
20
Q

what happens when the scanner detects the changes in FMRI?

A

• The scanner then sends the info to the computer to create a map of activation to show changing levels of neural activity in different brain areas as tasks are being completed.

21
Q

what does CAT scan stand for?

A

Computerised Axial Tomography

22
Q

what does a CAT scan do?

A

CAT scans use a series of X-ray beams passed through the head from different angles, creating cross-sectional images of the brain showing the structure, but not the function.

23
Q

when is a CAT scan useful?

A

This is useful for detecting areas of brain damage following an accident or positioning of tumours

24
Q

what are the pros of using CAT scans?

A
  • Quick and gives accurate details of brain structure
    • Non-invasive
    • May remove the need for exploratory surgery
25
Q

what is a problem with using CAT scans?

A

• Involves x-rays and so should be used sparingly

26
Q

why may PET scans be considered ethical?

A

They are ethical up to appoint because they are
relatively non-evasive compared with surgery;
images are taken from outside the body.

27
Q

how are PET scans reliable?

A

PET scans are reliable; they are replicable and the

same areas are highlighted.

28
Q

why might PET scans be considered slightly unethical?

A

• Can be thought of as slightly invasive due to
injection of radioactive tracer. They can be
distressing. Ethical guidelines must be followed e.g.
informed consent and having a good reason for
carrying it out.

29
Q

how are PET scans valid?

A

PET scans are valid because they appear to measure
what they claim to. Validity is not easy to check
when it comes to cognitive functions such as
language. However, studying speech using PET
scans has reconfirmed previous findings

30
Q

why are PET scans only valid up to a point?

A

it is hard to claim from a scan exactly

which part of the brain is performing which function.

31
Q

what is a strength of using FMRI scans?

A

Its sensitivity to changes in blood flow make it very good at looking at brain functioning and structure.

32
Q

what makes it difficult to be sure where the function is in the brain?

A

Because the brain is never at rest, it is hard to be totally

sure which part of the brain is involved in what

33
Q

why are scans lacking of ecological validity?

A
  • the scanning takes place in an artificial setting it
    lowers ecological validity which means the pts may not
    show natural behaviour due to the situation being different to everyday life
34
Q

what are some risks with using FMRI?

A

someone with a pacemaker
would not be able to have one of these as the magnetic field can cause physical disruption to the heart and it can be claustrophobic

35
Q

what is a weakness with using FMRI?

A
  • tiny movements could ruin the scan

biological psychology (17 decks)

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