1. Radiology 401
MR Imaging of the Brain
John R. Hesselink, M.D.

2. MR System Components Computer Magnet RF Coil Gradient Gradient RF Coil
Transmitter
Gradient Amplifier
RF Coil
Gradient
Computer
Gradient
RF Coil
Magnet
Receiver
Digitizer

3. Source of Signal and Contrast
MR Imaging
Source of Signal and Contrast
Proton density
T1 relaxation time
T2 relaxation time
Flow effects

4. Spin-echo Pulse Sequence
Single Echo T1-weighted RF
Signal TR TE
1st
echo
2nd
echo

5. Spin-echo Pulse Sequence
Dual Echo T2-weighted RF
Signal TR TE
1st
echo
2nd
echo

6. T2-Weighted Images

7. Proton Density Weighted Images

8. Normal FLAIR Images
TR = 6000 msec, TI = 2000 msec, TE = 102 msec

9. T1-Weighted
Images

10. MR Signal of Brain Lesions

11. T1W
T2W
Solid
Brain
Lesion
PDW

12. T1W
Cystic
Lesion
FLAIR
T2W
236

13. Subacute
Hemorrhage
PDW
T1W
T2W

14. Acute
Hemorrhage
T2W
FLAIR
T1W
GRE

15. History: 9 y/o boy with prior head trauma
466

16. Hemorrhage Sequence
Gradient-echo

17. Fat or
Lipoma
T2W
PDW
T1W

18. 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

19. Diffusion Weighted Imaging
Acute Stroke Sequence
Diffusion Weighted Imaging

20. MR Angiography

21. MR Spectroscopy
Dx: Anaplastic astrocytoma > GBM

22. Brain Screening Protocol
Axial T2-weighted images
Axial FLAIR images
If normal:
Stop
If abnormal:
T1-weighted images
Gd-DTPA enhancement

23. with headaches & increasing confusion
History: 46 y.o. man
with headaches & increasing confusion 1 2
T2W
PDW

24. 4 3
T1W
T1W 5
{Page 2}
T1W / Gd

25. Increasing confusion {Page 3}6 7
Dx: Meningioma & right MCA infarct