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Chapter 1: Introduction
!"
"! ! ! # @ $ƪ* f + @ *f
z
DBz =
Gz @z
z
z
B0
DBx =
DBy =
Gy @y
Gx @x
y
y
y
x
x
x
Fig. 1.3 Magnetic gradients applied during an MRI examination
The gradient DBz =Gz @z during the application of the excitation magnetic field.
The gradient DBy =Gy @y during the phase encoding.
The gradient DBx =Gx @x during the FID measure.
zĆgradient
DBz on
time
0
yĆgradient
DBy on
time
T
xĆgradient
DBx on
time
FID measure
Application of Phase
encoding
the rotating
magnetic
field with the
RFĆpulse
Fig. 1.4 A time diagram for the application of magnetic field gradients. Readout of row
in the Fourier domain of nuclei density.
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@ $* w 6
Chapter 1: Introduction
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the kĆspace, (kx ,ky )
ky
kx
s(t) measures one row
of data in the kĆspace
Fig. 1.5 The measured signal s(t) measures one row in the 2D Fourier domain (kx ,ky ) of
the nuclei density f(x,y).
zĆgradient
DBz
time
yĆgradient
DBy
time
xĆgradient
DBx
FIDĆmeasure
and readout of
different kyĆrows:
time
Fig. 1.6 A time diagram for the application of magnetic field gradients. Readout of rows ky in the Fourier domain of nuclei density.
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