Neuroimaging

Question 1

Who discovered MRI?

Answer 1

Felix Block and Edward Mills Purcell

Question 2

What year was MRI discovered in?

Answer 2

1947

Question 3

In which year were the first clinical MRI images obtained?

Answer 3

1977

Question 4

Which molecule does MRI rely upon for imaging?

Answer 4

Water

Question 5

What type of energy is released to excite the protons in water in the body?

Answer 5

Radiofrequency pulse

Question 6

What does T1 refer to?

Answer 6

Longitudinal relaxation and realignment with magnetic field following radiofrequency pulse disturbance

Question 7

What does T2 refer to?

Answer 7

Transverse relaxation and the resumption of protons spinning around their own axis

Question 8

In T2 weighted images, what appears brighter?

Answer 8

Water componenets

Question 9

What are T2 weighted images useful for clinically?

Answer 9

Detecting pathology

Question 10

In T1 weighted images, what appears brighter?

Answer 10

High-fat content

Question 11

What are T1 weighted images useful for clinically?

Answer 11

Analysing anatomy

Question 12

How is a 3D image of the brain constructued?

Answer 12

Images from multiple planes are reassembled digitally

Question 13

How are different planes of view obtained in MRI?

Answer 13

By passing radiofrequency pulse through the head at different angles

Question 14

What is the average strength of an MRI scanner?

Answer 14

1 to 3 Tesla

Question 15

How can the study of vascular structures be enhanced?

Answer 15

Use of Gadolinium contrast

Question 16

What is gadolinium contrast used for?

Answer 16

Enhancing vascular structures

Question 17

How is gadolinium administered?

Answer 17

Intravenous infusion

Question 18

How does gadolinium perform in a magnetic field?

Answer 18

It is paramagnetic, it only has a magnetic field when in a strong magnetic field but does not retain any permanent magnetic properties

Question 19

How do structural and functional MRI differ?

Answer 19

Structural studies anatomy

Functional studies brain function

Question 20

What does fMRI detect?

Answer 20

Changes in blood oxygen level (BOLD)

Question 21

How can blood oxygen level be detected under MRI?

Answer 21

Deoxyhaemoglobin is paramagnetic but oxyhaemoglobin is not

Question 22

What are limitations associated with fMRI?

Answer 22

Indirect measure of activity

Assumes that change in blood flow is synonymous with activity

There is a delay between neuronal activity and blood flow response

Low temporal resolution

Cannot differentiate between axonal or dendritic activity causing BOLD signal

Question 23

How can fMRI be used in clinic?

Answer 23

Diagnosing brain death

Detecting consciousness in comatose patients

Question 24

How can fMRI be used in pharmacological research?

Answer 24

Can measure efficacy of drugs via titrating dosages and imaging

Question 25

How does positron emission tomography (PET) work?

Answer 25

Body is abundant in elements that have positron-emitting forms. Radioactive isotopes for these elements are injected, they have a short half-life and emit positrons that collide with electrons, resulting in photon emission that is detected by the scanner

Question 26

What is PET useful for assessing in clinic?

Answer 26

Molecular function and activity

Question 27

What does diffusion weighted MRI show?

Answer 27

Differentiation between abnormal diffusion of protons in damaged neurons

Question 28

What are diffusion weighted images useful for assessing?

Answer 28

Damage to tissues (after stroke)

Question 29

What is a limitation of PET?

Answer 29

It is an indirect measure of brain activity