BOLD fMRI

Question 1

What is oxygenated haemoglobin called?

Answer 1

Oxyhaemoglobin (Hb02

Question 2

What is deoxygenated haemoglobin called?

Answer 2

Deoxyhaemoglobin (Hbr)

Question 3

How does deoxyhaemoglobin affect MR signal?

Answer 3

Paramagnetic so decreases MR signal (a lot)

Question 4

How does oxyhaemoglobin affect MR signal

Answer 4

Diamagnetic so increases MR signal (a bit)

Question 5

How bright the BOLD fMRI signal is depends on what?

Answer 5

How oxygenated the blood is

As deoxyhaemoglobin makes the image darker (decreases the signal)

Question 6

Why does blood in a brain region become more oxygenated when stimulated?

Answer 6

Because cerebral blood flow increases which overcompensates for increases in oxygen consumption needed for activity, increasing cerebral blood volume (CBV) or total haemoglobin concentration (HbT)

Question 7

What are some advantages and disadvantages of MRI?

Answer 7

Advantages:
• No radioactivity

• High spatial resolution

Disadvantages:
• Expensive

• Invasive