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Gradients
•
Recall that the resonant frequency is
proportional to field strength
•
Magnetic gradient changes B
0
field
strength over distance
•
In MRI a linear gradient changes the
resonant frequency in a given direction
dy
dB G
y
0
=
0
0
B
γ
ω
=
dz
dB G
z
0
=
dx
dB G
x
0
=
)
(
0
x
xG B
+ =
γ
ω