Wearable MRI Nano-Tera annual meeting 04.05.2015 Christian Vogt Electronics Laboratory
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MRI – State of the art and goals
Electronics Laboratory
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MRI – State of the art and goals
[head coil: Wiggins et al., 96-Channel receive-only head coil for 3 Tesla: Design optimization and evaluation, Magnetic Resonance in Medicine, 2009] Electronics Laboratory
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Why a wearable receiver? Less noisy signal
Patient comfort
[centres.exeter.ac.uk] [http://genufix.com/knee-injuries/patella-problems/] [philips.com] Electronics Laboratory
New diagnosis options
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MRI principle
• Protons precess in B-field • Excitation frequency prop. B-field • Proton response at excitation frequency • Typical Frequency: 128 MHz at 3 T Electronics Laboratory
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Spatial encoding
Electronics Laboratory
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Challenges inside the MRI machine
13 kW RF pulses 100 T/s local magnetic field
0.5 -3 T static field (clinical) Image distortions due to magnetic components
changes
Electronics Laboratory
[http://www.healthcare.philips.com/main/products/mri/systems/multiva/specifications.wpd]
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A wearable device for MRI acquisition
Challenge: Strong EM interference → small size helps significantly Electronics Laboratory
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Custom designed LNA and receiver IC
7 mm
4 mm 4 mm Electronics Laboratory
7 mm |
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Custom designed LNA and receiver IC
4 mm
7 mm
4 mm 7 mm
MRI Receiver Gain steps 1 - 30 dB Noise figure 0.9 dB HM3,min 81.8 dB Dynamic range74.8 dB Size (mm) 4.7x4.2
(referred to LNA in, DR 1MHz BW)
Electronics Laboratory
Low noise Amplifier Power gain 20.8 dB Noise figure 0.7 dB HM3,min 79 dB Dynamic range75.3 dB Size (mm) 0.8x0.6 (referred to LNA in, DR 1MHz BW)
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Data transmission
Glass fiber transmission Non-magnetic transmitter 1 Gbit/s possible
Electronics Laboratory
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Signal acquisition/processing Process image offline
Electronics Laboratory
[ni.com, www.mirifica.it]
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A wearable device for MRI acquisition
Electronics Laboratory
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Optimization for EM environment
Power supply path
RF path
Electronics Laboratory
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Imaging setup
Electronics Laboratory
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Example data from a human brain Excitation
MR Signal
Electronics Laboratory
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Example reconstruction of Image Acquired signal in k-space (magnitude and phase)
Fourier Transform
Reconstructed Image
Crop signals to image size/bandwidth Align all received signals correctly in k-space Electronics Laboratory
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First images from the receiver
Electronics Laboratory
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Summary
Electronics Laboratory
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Outlook
Electronics Laboratory
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