1. 1. University Of Sheffield, Sheffield UK
Using MR imaging methods for measurement of 3He cells during optical pumping
Steven Parnell1, M.Deppe1, S.Boag2, M.Boyce2, S.Ajraoui1, J.Parra-Robles1 and J.Wild1
1. University Of Sheffield, Sheffield UK
2. ISIS, STFC, Didcot UK

2. Contents Introduction Review of previous work Diffusion coefficient
Simple gradient pulse sequence’s
Experimental setup
Results
Conclusions - Further work
12/11/2018
© The University of Sheffield

3. Motivation
Hyperpolarised gas used in MR but what can MR tell us about the physics ?
In-situ diagnostic ?
Investigate imaging prospects
Can we image cells without significant distortions?
Investigate temperature effects
Can we use MR for thermometry?
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© The University of Sheffield

4. Previous work
‘Diffusion affects the correspondence of frequency to position’
Other low field systems;
For example;
G. Tastevin and P-J.Nacher, The Journal of Chemical Physics 123, (2005)
On two-column slides the text size is reduced from 32 pt to 28pt
Increasing
Gradient
Strength
Pulsed gradient methods
-Echo’s
Saam et al. Chemical Physics Letters 263 (1996)
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© The University of Sheffield

5. Echo and diffusion sensitisation gradients along Z (B0 direction)
Gradient Echo RF t
ms
Gradient
Waveform Gz  t 
Readout
Diffusion RF
ms t
Gradient
Waveform Gz  t 
Readout
0.5ms ramp
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© The University of Sheffield

6. Diffusion coefficient
Chapman-Enskog
Self diffusion
Binary diffusion
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© The University of Sheffield

7. Diffusion coefficient
Chapman-Enskog
Self diffusion
Binary diffusion
@1.5 T Philips system
Vary p in a syringe under constant temperature
p 1/D
J.M.Wild and S.R.Parnell ISMRM Toronto, (2008), Poster no. 1743
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© The University of Sheffield

8. Diffusion coefficient
Chapman-Enskog
Self diffusion
Binary diffusion
Therefore D(T)  T3/2f(Ω)
Collision integral - dependent upon interaction potential between the gas atoms
? - Can we use D measurement to determine T?
12/11/2018
© The University of Sheffield

9. Experimental setup r√3 r = 15cm Cell Spectrometer details;
Display
Construct
RF pulse
DAQ Card
Duplexer
Read gradient
waveform
Amplifier
Tx/Rx coils
Gradient Coils
Cell
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Spectrometer details;
S.R.Parnell, E. B.Woolley, S.Boag, and C.D.Frost, Measurement Science & Technology 19 (2008)
r√3
r = 15cm
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© The University of Sheffield

10. Cells and coils
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© The University of Sheffield

11. Gradient echo 1-D Images
Cylindrical cell
1 D Slices
Larger gradients
Increase resolution
Increase edge enhancement
Image size for calibration of Gz?
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© The University of Sheffield

12. Gradient echo 1-D Images
Cylindrical cell
1 D Slices
Larger gradients
Increase resolution
Increase edge enhancement
Image size for calibration of Gz?
3.4x10-4Tm-1
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© The University of Sheffield

13. Diffusion coefficient measurement -Global
FID
-as function of gradient strength i.e. b
-recover envelope via digital quadrature
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© The University of Sheffield

14. Diffusion coefficient measurement -Global
FID
-as function of gradient strength i.e. b
-recover envelope via digital quadrature
P=0.92Bar
P=2.37Bar
12/11/2018
© The University of Sheffield

15. Thermometry via diffusion coefficient ?
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© The University of Sheffield

16. Thermometry via diffusion coefficient ?
Temperature dependence constant P
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© The University of Sheffield

17. Thermometry via diffusion coefficient ?
Temperature dependence constant P
Temperature dependence P=TRT/TPRT
12/11/2018
© The University of Sheffield

18. Thermometry via diffusion coefficient ?
12/11/2018
© The University of Sheffield

19. Spatial mapping of temperature
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© The University of Sheffield

20. Tx/Rx coil characterisation
Flip angle calibration
- Showing homogeneity
Optimal angle =60
Current angle =110
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© The University of Sheffield

21. Conclusions summary
Method for mapping spatial distribution of polarisation - Xe applications
Correlate with Faraday [Rb]
In situ temperature monitoring
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22. Comparison CW/Echo
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© The University of Sheffield