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

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

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? 12/11/2018 © The University of Sheffield

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, 064506 (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) 481-487 12/11/2018 © The University of Sheffield

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 12/11/2018 © The University of Sheffield

Diffusion coefficient Chapman-Enskog Self diffusion Binary diffusion 12/11/2018 © The University of Sheffield

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 12/11/2018 © The University of Sheffield

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

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 More information: You can crop a picture (trim slices from the side, top or bottom) by selecting on the slide the picture that you want to crop, going to the “format” menu, selecting “picture…” and in the “picture” dialog box clicking the “picture” button. This opens the crop options. The preview button allows you to see whether the crop achieves the effect you wanted. (If you have an old version of PowerPoint these controls may be located differently - refer to the PowerPoint Help menu.) Before importing a picture into your presentation save it in a suitable format (eg jpeg) at a resolution of 72 dots per inch if possible. This resolution keeps the size of the picture file small but still displays fine on screen – particularly important if you’re using several pictures, because half a dozen taken on a five megapixel digital camera and imported at full resolution could mean that your presentation is over 20 megabytes in size. This means it will take up unnecessary disk space, will be slow to open and run on many less powerful computers – and will be too big to e-mail. Spectrometer details; S.R.Parnell, E. B.Woolley, S.Boag, and C.D.Frost, Measurement Science & Technology 19 (2008) r√3 r = 15cm 12/11/2018 © The University of Sheffield

Cells and coils 12/11/2018 © The University of Sheffield

Gradient echo 1-D Images Cylindrical cell 1 D Slices Larger gradients Increase resolution Increase edge enhancement Image size for calibration of Gz? 12/11/2018 © The University of Sheffield

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 12/11/2018 © The University of Sheffield

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

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

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

Thermometry via diffusion coefficient ? Temperature dependence constant P 12/11/2018 © The University of Sheffield

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

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

Spatial mapping of temperature 12/11/2018 © The University of Sheffield

Tx/Rx coil characterisation Flip angle calibration - Showing homogeneity Optimal angle =60 Current angle =110 12/11/2018 © The University of Sheffield

Conclusions summary Method for mapping spatial distribution of polarisation - Xe applications Correlate with Faraday [Rb] In situ temperature monitoring 12/11/2018

Comparison CW/Echo 12/11/2018 © The University of Sheffield