MRI, fMRI and CT scans

Question 1

why is brain imagining useful

Answer 1

1. help us to understand the relationship between specific brain areas and their function
2. to locate areas affected by neurological disorders
3. help us develop new strategies to treat brain disorders

Question 2

how does a CT scan work

Answer 2

uses narrow-beam X rays ( ionising radiation )

Question 3

advantages of a CT scan

Answer 3

• non-invasive
• quicker and cheaper then an MRI
• can image soft tissues as well as bones
• suitable for patients with metal body parts

Question 4

disadvantages of a CT scan

Answer 4

• only gives frozen moment images
• looks at the structure of the brain rather than function
• cannot distinguish small structures within the brain
• not portable

Question 5

how does a MRI work

Answer 5

uses magnetic field and radio waves to detect soft tissues

Question 6

why is MRI better than CT

Answer 6

• produces better resolutions of soft tissues
• SD images can be assembled

Question 7

how does fMRI scans work

Answer 7

uses blood flow and oxygen metabolism to infer brain activity

Question 8

advantages of fMRI

Answer 8

• non-invasive
• doesn’t involve ionising radiation
• operates in real time
• provides information about the brain in action

Question 9

how does a fMRI scan work to show the brain in action

Answer 9

1. follows the uptake of oxygen in active brain areas as deoxyhaemoglobin absorbs the radio wave signal and oxyhemoglobin does not
2. an increase in a neutral activity in the brain results in an increased demand for oxygen which is why there is an increase in blood flow. this result less signal being absorbed
3. different areas of the brain will light up according to when they are active

Question 10

what are PET scans used for

Answer 10

• diagnosing health conditions
• finding out how an existing conditions is developing
• how effective is an ongoing treatment

Question 11

how does a PET scan identify the area of a brain which is active

Answer 11

1. detects pairs of gamma rays emiited form a radiotracer which has been placed in the boyd on a biologically active molcule
2. as the radiotracer is broken down it releases positrons whihc then collide with surrounding electrons
3. this results in the release of photons which is then detected by the PET scanner