MRI Flashcards
1
Q
Why do humans respond so well to MRI scans?
A
Because they utilise hydrogen nuclei and humans are 75% water
2
Q
How does an MRI machine work?
A
- Each proton has its own magnetic field so when a separate B field is applied the H will all align in the same direction as the field.
- radiowaves are applied at a specific frequency to induce resonance.
- Once they gain enough energy from this to protons can flip to a higher energy state meaning their own magnetic field flips to act in the opposite direction of the B field
- the radiowaves are removed for the nuclei to flip back, emitting radiowaves of the same frequency
- The time taken for these flips to be recorded is what builds the MRI image
3
Q
What is the frequency needed for resonance?
A
lamor frequency
f = 42.6x10^6 x B
4
Q
Why is the machine rotated around the patient?
A
To capture 3D images
