MRI & MRS Flashcards
1
Q
MRI relies on the magnetic properties of what atom to produce images?
A
Hydrogen atom - i.e. proton
2
Q
The positive charge of a spinning proton produces what?
A
A magnetic moment, μ
3
Q
In a magnetic field, the magnetic moment of a proton processes at what frequency?
A
The Larmor frequency
4
Q
RF coils are used to transmit pulses of what electromagnetic frequency into the body?
A
Radiofrequency excitation pulses
5
Q
Name the main components of an MRI machine.
A
- Superconducting magnet
- RF coils
- Magnetic field gradients
- RF receiver
- Computer
6
Q
The intensity of an MR image depends upon what factors?
A
- Water content
- Tissue structure
- Blood flow
- Perfusion
- Diffusion
- Paramagnetics
7
Q
What is the T2 relaxation time?
A
- The T2 of tissue determines how quickly the MRI signal decays away after the RF pulse
- T2 is dependent on water mobility and increases with oedema and demyelination
- T2 is reduced by the presence of paramagnetic ions - Fe from blood breakdown products, Gd from contrast agents
8
Q
What is T1 relaxation time?
A
- k
9
Q
What is the taxi driver effect?
A
- Taxi drivers’ brains monitored over years
- Increase in hippocampal volume over time
- Neurogenesis proposed to explain need for increased capacity of spatial memory
10
Q
A
