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MR Imaging of the Brain. Radiology 401. John R. Hesselink, M.D. MR System Components. Transmitter. Gradient Amplifier. RF Coil. Gradient. Computer. Gradient. RF Coil. Magnet. Receiver. Digitizer. Source of Signal and Contrast. Proton density T1 relaxation time T2 relaxation time
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MR Imaging of the Brain Radiology 401 John R. Hesselink, M.D.
MR System Components Transmitter Gradient Amplifier RF Coil Gradient Computer Gradient RF Coil Magnet Receiver Digitizer
Source of Signal and Contrast Proton density T1 relaxation time T2 relaxation time Flow effects MR Imaging
RF TR TE Signal Spin-echo Pulse Sequence Single Echo T1-weighted 1st echo 2nd echo
RF TR TE TE Signal Spin-echo Pulse Sequence Dual Echo T2-weighted 1st echo 2nd echo
Normal FLAIR Images TR = 6000 msec, TI = 2000 msec, TE = 102 msec
T1-Weighted Images
T1W T2W Solid Brain Lesion PDW
T1W Cystic Lesion FLAIR T2W 236
Subacute Hemorrhage PDW T1W T2W
T2W FLAIR Acute Hemorrhage T1W GRE
Hemorrhage Sequence Gradient-echo
Fat or Lipoma T2W PDW T1W
MR Signal Intensities T2WI PD/FLAIR T1WI Solid mass Bright Bright Dark Cyst Bright Dark Dark Subacute blood Bright Bright Bright Acute & chronic blood Dark Dark Gray Fat Dark Bright Bright
Acute Stroke Sequence Diffusion Weighted Imaging
MR Spectroscopy Dx: Anaplastic astrocytoma > GBM
Axial T2-weighted images Axial FLAIR images If normal: Stop If abnormal: T1-weighted images Gd-DTPA enhancement Brain Screening Protocol
History: 46 y.o. man with headaches & increasing confusion 2 1 T2W PDW
4 3 T1W T1W 5 {Page 2} T1W / Gd
Increasing confusion {Page 3} 6 7 Dx: Meningioma & right MCA infarct