Radiology 401 MR Imagingof the Brain John R. Hesselink, M.D. MR System Components Computer Magnet RF Coil Gradient Gradient RF Coil
Transmitter Gradient Amplifier RF Coil Gradient Computer Gradient RF Coil Magnet Receiver Digitizer Source of Signal and Contrast
MR Imaging Source of Signal and Contrast Proton density T1 relaxation time T2 relaxation time Flow effects Spin-echo Pulse Sequence
Single Echo T1-weighted RF Signal TR TE 1st echo 2nd echo Spin-echo Pulse Sequence
Dual Echo T2-weighted RF Signal TR TE 1st echo 2nd echo T2-Weighted Images Proton Density Weighted Images Normal FLAIR Images TR = 6000 msec, TI = 2000 msec, TE = 102 msec T1-Weighted Images MR Signal of Brain Lesions T1W T2W Solid Brain Lesion PDW T1W Cystic Lesion FLAIR T2W 236 Subacute Hemorrhage PDW T1W T2W Acute Hemorrhage T2W FLAIR T1W GRE History: 9 y/o boy with prior head trauma
466 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 Diffusion Weighted Imaging
Acute Stroke Sequence Diffusion Weighted Imaging MR Angiography MR Spectroscopy Dx:Anaplastic astrocytoma > GBM Brain Screening Protocol
Axial T2-weighted images Axial FLAIR images If normal: Stop If abnormal: T1-weighted images Gd-DTPA enhancement with headaches & increasing confusion
History:46 y.o. man with headaches & increasing confusion 1 2 T2W PDW 4 3 T1W T1W 5 {Page 2} T1W / Gd Increasing confusion {Page 3}
6 7 Dx:Meningioma & right MCA infarct