In-room imaging and MR planning

180 o

90 o

position encoding

Position decoding

readout

Fully refocussed signal Diffusion-weighted signal

With diffusion: spins undergo continuous motion 1. All spins accrue phase (with varying speed) according to changing position

In the presence of diffusion, the resulting signal will be lower.

More diffusion = Less signal

2. 180 ° pulse flips magnetization

3. No complete realignment

B -ΔB

B

B +ΔB

Animations courtesy of Karla Miller, Oxford