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arXiv · 0705.0661

SQUID-based instrumentation for ultra-low-field MRI

V. S. Zotev·A. N. Matlashov·P. L. Volegov·A. V. Urbaitis·M. A. Espy·R. H. Kraus Jr
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Abstract

Magnetic resonance imaging at ultra-low fields (ULF MRI) is a promising new imaging method that uses SQUID sensors to measure the spatially encoded precession of pre-polarized nuclear spin populations at a microtesla-range measurement field. In this work, a seven-channel SQUID system designed for simultaneous 3D ULF MRI and magnetoencephalography (MEG) is described. The system includes seven second-order SQUID gradiometers, characterized by magnetic field resolutions of 1.2 - 2.8 fT/rtHz. It is also equipped with five sets of coils for 3D Fourier imaging with pre-polarization. Essential technical details of the design are discussed. The system's ULF MRI performance is demonstrated by multi-channel 3D images of a preserved sheep brain acquired at 46 microtesla measurement field with pre-polarization at 40 mT. The imaging resolution is 2.5 mm x 2.5 mm x 5 mm. The ULF MRI images are compared to images of the same brain acquired using conventional high-field MRI. Different ways to improve imaging SNR are discussed.

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V. S. Zotev, A. N. Matlashov, P. L. Volegov, A. V. Urbaitis, M. A. Espy, R. H. Kraus Jr. 2007-07-30. SQUID-based instrumentation for ultra-low-field MRI. https://doi.org/10.1088/0953-2048%2F20%2F11%2Fs13

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