MRI Portable Devices for Medical Environments. Javier Alonso - - PowerPoint PPT Presentation

Javier Alonso Valdesueiro. Ph.D.

Science and Technology Faculty, Electricity and Electronics UPV/EHU.

MRI Portable Devices for Medical Environments.

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lfpMRI

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So… what for today?

• RF-MAFS project. Or how we deal with nuclear interactions,

magnetic susceptibility changes, patient movements, etc. in MRI experiments at low field.

• MRI-Magnetsome project. Or how we increase SNR of MR

images at the same time we don’t poison anyone Also it would be nice if we could target cancer cells in the process.

• lfpHyperpol project. Or how we plan to increase our NMR

signal so we can carry out spectroscopy wit our equipment.

Spectral and Image Resolution

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Resolution of the Spectral lines in Solid State NMR:

• Dipolar Interaction.
• Chemical Shift Anisotropy.
• Quadrupolar Interaction.

In MRI we add:

• Magnetic susceptibility.
• Magnetic field in-

homogeneities.

• Patient movements.

[1] University of Ottawa NMR Facility Blog, June 4, 2008. [2] MRI Artifacts Seminar, ICAN School of Medicine at Mount Sinai Hospital, New York

[1] [2]

Magic Angle Spinning

Magic Angle Spinning:

• Sample Tilted 54.74° wrt the

main magnetic field.

• Sample Spun at frequencies

between 15 kHz and 100 kHz.

• DDC cancelled and CSA and

MSC averaged.

[1] University of Ottawa NMR Facility Blog, June 4, 2008.

[1]

Spin the Sample:

[2]

[2] Wind R.A., Hu J.Z., Rommereim D.N., “High-resolution 1H NMR spectroscopy in a live mouse subjected to 1.5 Hz magic angle spinning,” Magn Reson Med. vol 50(6), pp. 1113-9, 2003 December.

(a) The mouse-MAS probe; (b) 85 MHz 1H NMR image of the part of the (live) mouse body between the arrows shown in (a). 85MHz in-vivo 1H spectra of a 8mm x 8mm x 8mm volume in the liver of a live indicated as 1 using (a) static NMR (b) 4Hz spinning technique and (c) ex-vivo NMR .

Spin the Sample:

Magic Angle Field Spinning

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[3] McGinley J. V. M., Ristic M., Young I. R., “A permanent MRI magnet for magic angle imaging having its field parallel to the poles, ” J. Magn.

• Reson. Vol. 271, pp. 60-67, 2016

[4] Sakellariou D., Hugon C., Guiga A., Aubert G., Cazaux S., Hardy P., “Permanent magnet assembly producing a strong tilted homogeneous magnetic field: towards magic angle field spinning NMR and MRI,” Magn. Reson. Chem. Vol. 48 (12), pp. 903-908, 2010

[4]

B0=Bz’ x y z z’ Gz’=dB0 /dz’=dBz’ /dz’

θ θ ωr

z z z’

θ

RF Probe BRF Rotating Power transfer

[3]

Spin the Magnetic Field:

Very Low Spinning Frequencies:

Forget to average completely the anisotropies.

Enormous Weight and Instrumentation:

Forget to deploy the device in Mobile/Emergency medical environments.

RF-MFAS Concept

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• 2 RF coils fed in opposite phase

producing Bt.

• 1 Electromagnet producing Bl.

evaluating B0

• NMR spectrometer and probe.
• MRI Gradient system.

Magnetic System:

• Maximum Magnetic Field Intensity.
• Cylindrical Volume of Homogeneity 30x30mm.
• Proof of Concept.
• Ongoing work.

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Diameters:

• Out. Coil OD/ID: 70.8/68.
• Inn. Coil OD/ID: 66.8/64.

Fields:

• Out. Coil By ~ 1.4 mT/Arms.
• Inn. Coil Bx ~ 1.6 mT/Arms.

Rotating Magnetic Field:

1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8

• 200 -150 -100 -50

50 100 150 200 Bx a = 28º (mT) By a = 29.5º (mT) Bx (mT) By (mT) Bx (mT) By (mT) Z (mm)

RF-MFAS Electromagnet

RF-MFAS Electromagnet

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• Strong angular

dependence.

• Miss-alignment

between layers.

• Angular current

distribution.

• 0.01

0.01 0.02 0.03 0.04

• 150
• 100
• 50

50 100 Error B1 B2/B1

Error Z (mm)

• 0.005

0.005 0.01 0.015 0.02 0.025 0.03 0.035

• 150
• 100
• 50

50 100 Error B2 B1/B2

Error Z (mm)

• 0.01

0.01 0.02 0.03 0.04 0.05 0.06

• 120
• 80
• 40

40 80 120 0º 60º 120º 180º 240º 300º

D1 Z (mm)

• 0.01

0.01 0.02 0.03 0.04 0.05 0.06

• 120
• 80
• 40

40 80 120 0º 60º 120º 180º 240º 300º

D2 Z (mm)

RF-MFAS Electromagnet

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Longitudinal Magnetic Field:

Design:

• Simulations and
• ptimizations.
• Power Constraint

30W.

• Diameter constraint

280 mm. Construction:

• 3D printed parts.
• Home-made

winding.

0.02 0.04 0.06 0.08 0.1

• 20
• 15
• 10
• 5

5 10 15 20 90 mm 90/140 mm 110/140 mm 110/140* mm

DB ( % ) z ( mm )

2 rs1 2 rs2 s1

r

Z (m) Z (m) B (mT) x (m)

a) b) c)

s2

r

x (m)

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• Homogeneity region

extends 80 mm.

• Bz ~ 2mT/A.
• Same 15 mm axis

measured.

• Noise around 60µT.

Longitudinal Magnetic Field:

RF-MFAS Electromagnet

1.6 1.7 1.8 1.9 2 2.1 2.2

• 80
• 60
• 40
• 20

20 40 60 80 Bz Simulations Bz Central Z-Axis

Bz (mT/Arms) Z (mm)

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RF-MFAS Electromagnet

Longitudinal Magnetic Field:

• Very good cylindrical symmetry.
• Deviation at z = 0 less than 60µT.
• 0.0002

0.0002 0.0004 0.0006 0.0008 0.001 0.0012 0.0014

• 20
• 15
• 10
• 5

5 10 15 20 Central HS 15 mm HS at 0º 15 mm HS at 60º 15 mm HS at 120º 15 mm HS at 180º

Error Z (mm)

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RF-MFAS Spectrometer

This is where we are:

LNMR 1Ω

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RF-MFAS Spectrometer

This is where we are:

Coils:

• TX Coil: 3 turns saddle coil 14

mm diameter.

• RX Coil: 11 turns DHD coil tilted

at 38°.

• 40 dB isolation when position

is optimized. Amplification Chain:

• Gv = 10 for each stage.
• 3 stages protected by crossed

diodes.

• SR560 added at the end of the

chain.

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T1,2-MR Image enhancement

TR (msec) TE (msec) T1-Weighted (short TR and TE) 500 14 T2-Weighted (long TR and TE) 4000 90 Flair (very long TR and TE) 9000 114 Tissue T1-Weighted T2-Weighted Flair CSF Dark Bright Dark White Matter Light Dark Gray Dark Gray Cortex Gray Light Gray Light Gray Fat Bright Light Light Inflammation (infection, demyelinatio n) Dark Bright Bright

[5]

[5]http://casemed.case.edu/clerkships/neurology/web%20neur

• rad/mri%20basics.htm

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T1,2-MR Image enhancement

• Biological hazard at high concentrations.
• Low concentrations (mM) typically

used.

• Low concentrations lead to long pulse

sequences and low contrast changes.

What the Nature Offers

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T1,2-MR Image enhancement

Our Approach:

[6] M. A. Abakumov, N. V. Nukolova, M. Sokolsky-Papkov, S. A. Shein, T. O. Sandalova, H. M. Vishwasrao, N. F. Grinenko, I. L. Gubsky, A. M. Abakumov, Al. V. Kabanov, Vl. P. Chekhonin, “VEGF-targeted magnetic nanoparticles for MRI visualization of brain tumor,” Nanomed. Nanotech. Bio. Med., vol. 11 (4), pp. 825-833, 2015.

[6]

• Step 1: Functionalization of the shell.✔
• Step 2: Analysis of the attached molecules. ✔
• Step 3: absorption rate of the cancer cells.
• Step 4: In-vitro imaging of cells

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T1,2-MR Image enhancement

Lunch Time!!!

50 100 150 200 20 30 40 50 60 70 80 90 100 Porcentaje de concentracion concentracion [mM] % control extracc. 50 100 150 200 50 100 150 Concentraciones totales extraidas concentracion [mM] mM

200 mM 100 mM 50 mM 25 mM 0 mM 35 µg/mL

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Low Field Hyperopolarization

[7]

[7] A. Ajoy, R. Nazaryan, E. Druga, K. Liu, A. Aguilar, B. Han, M. Gierth, J. T. Oon, B. Safvati, R. Tsang, J. H. Walton, D. Suter, C. A. Meriles, J. A. Reimer, and A. Pines, “Room temperature “Optical Nanodiamond Hyperpolarizer”: physics, design and operation,” arXiv: 1811.10218v1, 2018.

• Nano-Particle base Hyperpolarizator.
• Portable and Cryo-Free apparatus.
• Future Funding applications

RF Group

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MIMASPEC Group

Beatriz Sisniega, MSc.: Magnetic Measurements and Magnet design. Julen Urtaza, Gr. St.: Electronics and positioning system. Juan Mari Collantes: Project Coordination and RF insight. Libe, Popi, Aitziber, Nerea, Joaquín: Support and discussions. Irati Rodrigo: Measurment system and callibration. Jorge Pérez: Numerical Simulations

Acks

Funding:

MSCA-IF: RF MAFS project with action number 750445. Basque Country Government: Education, Politics, Language and Culture Department of the Basque Country Government, through project with ref. IT1104-16. Lourdes Marcano: Magnetsome growth and manipulation

GMMM at UPV/EHU

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THANK YOU

Engineering for Medical

• Applications. Sep. 11th-13th

Bilbao, Spain.

Measurement System

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Inner DHD Coil Spatial Measurements

1.2 1.3 1.4 1.5 1.6 1.7

• 100
• 50

50 100 150 Bx int (mT) Bx pos1 (mT) Bx pos6 (mT) Bx pos5 (mT) Bx pos4 (mT) Bx pos3 (mT) Bx pos2 (mT) Bx (mT) Z (mm)

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Outer DHD Coil Spatial Measurements

1.2 1.3 1.4 1.5 1.6 1.7

• 100
• 50

50 100 150 By pos2 (mT) By pos3 (mT) By pos4 (mT) By pos5 (mT) By pos6 (mT) By pos1 (mT) By int (mT) By (mT) Z (mm)

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Measurement System

Power Matching Network

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4400 4500 4600 4700 4800 4900

• 2

2 4 6 8 10 12 x 10

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Espectro CH3 Control f [kHz] a.u. 200 mM 100 mM 50 mM 25 mM

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4400 4500 4600 4700 4800 4900

• 5

5 10 15 20 x 10

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f [kHz] a.u Espectro CH3 despues de Extraccion 200 mM 100 mM 50 mM 25 mM