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Abstract #0484

Enhancing B0 Homogeneity in Low-Field MRI: Experimental Study on the Thermal Dependence of Halbach Permanent Magnets

Pavel Povolni1, Kai Buckenmaier1, Sergej Maltsev1, and Klaus Scheffler1,2
1High‑Field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tuebingen, Germany, 2Department for Biomedical Magnetic Resonance, University of Tübingen, Tübingen, Germany

Synopsis

Keywords: Low-Field MRI, Low-Field MRI

Motivation: Temperature-dependent B0 drift limits the use of sequences (e.g. bSSFP) in low-field MRI, preventing the full utilization of the system's potential.

Goal(s): The temperature of the used NdFeB-magnets is stabilized through active water cooling in a Halbach slice, with B0-drift measured and simulated.

Approach: A Halbach slice prototype with water-cooled magnets and heating capabilities was designed. The magnetic field was mapped with Hall sensors, while temperature, pressure, and flow sensors characterized the cooling performance.

Results: Experimental results confirmed expected homogeneity changes with temperature, while identifying a feasible variant of cooling method for future Halbach MRI systems.

Impact: Dynamic temperature-dependent B0-drift of permanent magnet-based low-field MRI represents a significant challenge, especially with bSSFP sequences. Our experimental study, complemented by the construction of a prototype, demonstrates a solution to this problem through active water cooling of the magnets themselves.

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