3D printing of ferromagnetic passive shims for field shaping in magnetic resonance imaging

• Published in: Journal of magnetic resonance (1997) Vol. 363; p. 107702
• Main Authors: Vanduffel, Hanne, Goudard, Quentin, Vanduffel, An, Basov, Sergey, Van Bael, Margriet J., Parra-Cabrera, Cesar, Gsell, Willy, Oliveira-Silva, Rodrigo, Matavz, Aleksander, Vanduffel, Wim, Himmelreich, Uwe, Sakellariou, Dimitrios, Ameloot, Rob
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.06.2024
• Subjects: 3D printing; Additive manufacturing; Binder jetting; Ferromagnetic; MRI; Passive shimming; Subject-specific; Passive shimming; MRI; Binder jetting; Additive manufacturing; Ferromagnetic; Subject-specific; 3D printing
• ISSN: 1090-7807; 1096-0856; 1096-0856
• DOI: 10.1016/j.jmr.2024.107702

Voxel-based binder jetting is explored for 3D printing ferromagnetic passive shims for magnetic resonance imaging (MRI). The resulting shims demonstrate promising capabilities in generating specific magnetic field distributions and showcasing minimal dimensional inaccuracies, enabling shim voxels to be at least 25 times smaller than previously reported. Passive shims 3D printed this way can potentially improve the performance of MRI acquisitions. [Display omitted] •Binder-jetting 3D printing corrects B0 in MRI with ferromagnetic ink deposition.•Printed shims generate magnetic fields corresponding to 2nd-order SHE terms.•The electrically insulating ink eliminates eddy currents and heating risk. Magnetic Resonance Imaging (MRI) often encounters image quality degradation due to magnetic field inhomogeneities. Conventional passive shimming techniques involve the manual placement of discrete magnetic materials, imposing limitations on correcting complex inhomogeneities. To overcome this, we propose a novel 3D printing method utilizing binder jetting technology to enable precise deposition of a continuous range of concentrations of ferromagnetic ink. This approach grants complete control of the magnitude of the magnetic moment within the passive shim enabling tailored corrections of B0 field inhomogeneities. By optimizing the magnetic field distribution using linear programming and an in-house written Computer-Aided Design (CAD) generation software, we printed shims with promising results in generating low spherical harmonic corrections. Experimental evaluations demonstrate feasibility of these 3D printed passive shims to induce target magnetic fields corresponding to second-order spherical harmonic, as evidenced by acquired B0 maps. The electrically insulating properties of the printed shims eliminate the risk of eddy currents and heating, thus ensuring safety. The dimensional fabrication accuracy of the printed shims surpasses previous methods, enabling more precise and localized correction of subject-specific inhomogeneities. The findings highlight the potential of binder-jetted 3D printed passive shims in MRI shimming as a versatile and efficient solution for fabricating passive shims, with the potential to enhance the quality of MRI imaging while also being applicable to other types of Magnetic Resonance systems.