Advanced Pipeline for Designing Multi-Locus TMS Coils with Current Density Constraints

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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IEEE Transactions on Biomedical Engineering
Objective: This work aims for a method to design manufacturable windings for transcranial magnetic stimulation (TMS) coils with fine control over the induced electric field (E-field) distributions. Such TMS coils are required for multi-locus TMS (mTMS). Methods: We introduce a new mTMS coil design workflow with increased flexibility in target E-field definition and faster computations compared to our previous method. We also incorporate custom current density and E-field fidelity constraints to ensure that the target E-fields are accurately reproduced with feasible winding densities in the resulting coil designs. We validated the method by designing, manufacturing, and characterizing a 2-coil mTMS transducer for focal rat brain stimulation. Results: Applying the constraints reduced the computed maximum surface current densities from 15.4 and 6.6 kA/mm to the target value 4.7 kA/mm, yielding winding paths suitable for a 1.5-mm-diameter wire with 7-kA maximum currents while still replicating the target E-fieldswith the predefined 2.8% maximum error in the FOV. The optimization time was reduced by two thirds compared to our previous method. Conclusion: The developed method allowed us to design a manufacturable, focal 2-coil mTMS transducer for rat TMS impossible to attain with our previous design workflow. Significance: The presented workflow enables considerably faster design and manufacturing of previously unattainable mTMS transducers with increased control over the induced E-field distribution and winding density, opening new possibilities for brain research and clinical TMS.
| openaire: EC/H2020/810377/EU//ConnectToBrain
Coil design, coil optimization, Coils, Current density, current density, mTMS, multi-locus TMS, Optimization, TMS, transcranial magnetic stimulation, Transcranial magnetic stimulation, Transducers, Windings, Wires
Rissanen , I J , Souza , V H , Nieminen , J O , Koponen , L M & Ilmoniemi , R J 2023 , ' Advanced Pipeline for Designing Multi-Locus TMS Coils with Current Density Constraints ' , IEEE Transactions on Biomedical Engineering , vol. 70 , no. 7 , pp. 2025-2034 .