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Department of RadiologyUniversity of California
San Diego
John R. Hesselink, M.D.
MR ImagingMR Imaging of the Brain
MR System Components
Computer
Gradient Amplifier
Receiver
Transmitter
Digitizer
RF Coil
Gra
die
nt
RF Coil
Grad
ient
Magnet
MR Imaging
Proton density
T1 relaxation time
T2 relaxation time
Flow effects
Source of Signal and Contrast
Spin-echo Pulse SequenceSingle Echo T1-weighted
RF
Signal
TR
TE
1st
echo2nd
echo
Spin-echo Pulse SequenceDual Echo T2-weighted
1st
echo2nd
echo
RF
Signal
TR
TE
TE
T2-Weighted Images
Proton Density Weighted Images
Normal FLAIR Images
TR = 6000 msec, TI = 2000 msec, TE = 102 msec
T1-Weighted Images
MR Signal ofMR Signal ofBrain LesionsBrain Lesions