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B1 Mapping

Exercise 4-1

Building intuition: can you guesstimate B1 from the raw data?

Two images at 60° and 120°: a quiz on where B1 is high or low, and why the double angle works.

Exercise 4-2

Registering qMRI measurements between each other: DAM example

Register a double angle pair to match an AFI B1 map: a refresher from Lab 4.

Exercise 4-3

Building intuition: why do the two AFI signals depend on B1?

One magnetization vector through an AFI cycle, its two readouts locked in.

Exercise 4-4

How does an off-resonance pulse add phase?

Bloch–Siegert: frames of reference, a strong pulse off resonance, the measured images, the phase it adds, and why two offsets cancel B0.

Exercise 4-5

B1 map application example: VFA T1 mapping

Can VFA fit for B1 instead of measuring it? Place your angles, add noise, compare with an AFI map.

Exercise 4-6

Filtering B1 maps: why, how, and what can go wrong?

Spot the flaws in DA, AFI and BS maps, pick median or Gaussian, make three methods agree, then filter a map with bright vessels.

Changing slides: move the mouse to the far left or right edge of the window until a grey bar appears, then click it to go back or forward. Space and Page Down also move forward.