brain scanning

Question 1

what are the three types of scans?

Answer 1

fmri
pet
cat

Question 2

what does a pet scan show?

Answer 2

activity

Question 3

what does an fmri scan show?

Answer 3

function

Question 4

what does a cat scan show?

Answer 4

structure

Question 5

how does a pet scan work?

Answer 5

patient is injected with a tracer
tracer is radioactive versions of chemical that is used up during brain activity such as glucose and water
tracer injected into blood stream and reached brain after one minute
brain cells start to uptake the oxygen in the chemicals and tracer begins to decay after 10-15 minutes
as tracer decays it releases minute amounts of radioactivity in the from of positrons
active areas use most oxygen therefore leaving behind most positrons
positrons create a signal that is able to be picked up by the machine
radioactivity received in the form of gamma rays as positrons collide with electrons

Question 6

what is the patient injected with in a pet scan?

Answer 6

a radioactive version of chemicals that are used up during brain activity such as glucose and water

Question 7

how long does it take for the tracer to reach the brain? (PET)

Answer 7

one minute

Question 8

how long does it take the tracer to decay? (PET)

Answer 8

10-15 minutes

Question 9

how does the tracer decay? (PET)

Answer 9

the brain cells start to uptake oxygen in the tracer

Question 10

what is given off as the tracer decays? (PET)

Answer 10

positrons

Question 11

in what form is the signal received from a pet scan and why?

Answer 11

gamma rays

produced as the positrons collide with electrons

Question 12

what happens in a cat scan?

Answer 12

usually takes around 20-30 minutes
might be injected with a dye that shows bloodstream
it involved a series of X-rays beings passed through the head at different angles to create a cross sectional image

Question 13

what is used order to create images in a cat scan?

Answer 13

a series of X-rays at different angles

Question 14

how does an fmri scan work?

Answer 14

involves looking at blood flow as it is associated with brain activity
head is placed in a very powerful electro magnet
inside the magnetic field the nuclei within hydrogen in water align themselves in the direction of the magnetic field
as neural activity increases so doe the demand for oxygen and therefore blood flow
heamoglobin carries oxygen as it carries oxygen it repels magnetic field
as it becomes deoxygenised as body used oxygen it follows the direction of the magnetic field
scanner detects these changes and creates images

Question 15

what is looked at in an fmri scan?

Answer 15

blood flow as it is associated with brian activity

Question 16

what equipment is used in an fmri?

Answer 16

a very powerful electromagnet

Question 17

what aligns in the direction of the magnetic field? (FMRI)

Answer 17

nuclei within hydrogen in water

Question 18

what happens to haemoglobin?

Answer 18

it carries oxygen as it does son it repels to magnetic field but when deoxygenated it follows the direction of the magnetic field

Question 19

as neural activity increases what else increase? (FMRI)

Answer 19

blood flow and demand for oxygen

Question 20

why are brian scans ethical?

Answer 20

relatively non invasive compared to surgery

images outside the body

Question 21

what is a difference between pet and fmri in evaluation?

Answer 21

in pet movement does not ruin the scan whereas in fmri tiny movements have the ability to make the whole scan invalid

Question 22

what is weakness of cat scan in terms of health?

Answer 22

you are subject to the amount of radiation that you would be exposed to in a certain month or years in twenty minutes

Question 23

what is a health risk with fmri?

Answer 23

if someone has a pace maker and has not told someone it can have catastrophic impacts due to the strength of the electromagnet

Question 24

what is a weakness in trying to locate function/

Answer 24

brian is never at rest so it is hard to see which areas are specifically linked to a certain thing