Abstract

Objective: Implementing electrophysiological recordings within an MRI environment is challenging due to complex interactions between recording probes and MRI-generated fields, which can affect both safety and data quality. This study aims to develop and evaluate a hybrid electromagnetic (EM) simulation framework for efficient and accurate assessment of such interactions. Methods: A hybrid EM strategy integrating the Huygens’ Box (HB) method with sub-gridding was implemented in an FDTD solver (Sim4Life). RF coil models for mouse and rat head were simulated with and without intracortical (IC) and epicortical (EC) graphene-based micro-transistor arrays. Three-dimensional multi-layered probe models were reconstructed from two-dimensional layouts, and transmit field (B₁⁺), electric field (E), and specific absorption rate (SAR) distributions were evaluated. Performance was benchmarked against conventional full-wave multi-port (MP) simulations using Bland–Altman analysis and voxel-wise percentage differences. Results: HB simulations reduced computational time by approximately 70–80%, while preserving spatial patterns of |B₁⁺|, |E|, and SAR, including transmit-field symmetry and localized high-field regions. Deviations from MP were minimal for |B₁⁺| (median Δ% 0.02–0.07% in mice, −3.7% to −1.7% in rats) and modest for |E| and SAR, with absolute SAR values remaining well below human safety limits. Graphene-based arrays produced negligible effects on RF transmission and SAR deposition. Conclusion: The HB approach enables computationally efficient, high-resolution evaluation of EM interactions involving microscopic probes in MRI environments, supporting simulations that are otherwise impractical with full-wave MP modeling. Significance: HB provides a reliable framework for preclinical safety assessment and design optimization of graphene-based implants, facilitating accelerated translation of microscopic implant simulations toward human-scale applications in the future.

Abstract

Objective: Implementing electrophysiological recordings within an MRI environment is challenging due to complex interactions between recording probes and MRI-generated fields, which can affect both safety and data quality. This study aims to develop and evaluate a hybrid electromagnetic (EM) simulation framework for efficient and accurate assessment of such interactions. Methods: A hybrid EM strategy integrating the Huygens’ Box (HB) method with sub-gridding was implemented in an FDTD solver (Sim4Life). RF coil models for mouse and rat head were simulated with and without intracortical (IC) and epicortical (EC) graphene-based micro-transistor arrays. Three-dimensional multi-layered probe models were reconstructed from two-dimensional layouts, and transmit field (B₁⁺), electric field (E), and specific absorption rate (SAR) distributions were evaluated. Performance was benchmarked against conventional full-wave multi-port (MP) simulations using Bland–Altman analysis and voxel-wise percentage differences. Results: HB simulations reduced computational time by approximately 70–80%, while preserving spatial patterns of |B₁⁺|, |E|, and SAR, including transmit-field symmetry and localized high-field regions. Deviations from MP were minimal for |B₁⁺| (median Δ% 0.02–0.07% in mice, −3.7% to −1.7% in rats) and modest for |E| and SAR, with absolute SAR values remaining well below human safety limits. Graphene-based arrays produced negligible effects on RF transmission and SAR deposition. Conclusion: The HB approach enables computationally efficient, high-resolution evaluation of EM interactions involving microscopic probes in MRI environments, supporting simulations that are otherwise impractical with full-wave MP modeling. Significance: HB provides a reliable framework for preclinical safety assessment and design optimization of graphene-based implants, facilitating accelerated translation of microscopic implant simulations toward human-scale applications in the future.

Abstract

Objective: Implementing electrophysiological recordings within an MRI environment is challenging due to complex interactions between recording probes and MRI-generated fields, which can affect both safety and data quality. This study aims to develop and evaluate a hybrid electromagnetic (EM) simulation framework for efficient and accurate assessment of such interactions. Methods: A hybrid EM strategy integrating the Huygens’ Box (HB) method with sub-gridding was implemented in an FDTD solver (Sim4Life). RF coil models for mouse and rat head were simulated with and without intracortical (IC) and epicortical (EC) graphene-based micro-transistor arrays. Three-dimensional multi-layered probe models were reconstructed from two-dimensional layouts, and transmit field (B₁⁺), electric field (E), and specific absorption rate (SAR) distributions were evaluated. Performance was benchmarked against conventional full-wave multi-port (MP) simulations using Bland–Altman analysis and voxel-wise percentage differences. Results: HB simulations reduced computational time by approximately 70–80%, while preserving spatial patterns of |B₁⁺|, |E|, and SAR, including transmit-field symmetry and localized high-field regions. Deviations from MP were minimal for |B₁⁺| (median Δ% 0.02–0.07% in mice, −3.7% to −1.7% in rats) and modest for |E| and SAR, with absolute SAR values remaining well below human safety limits. Graphene-based arrays produced negligible effects on RF transmission and SAR deposition. Conclusion: The HB approach enables computationally efficient, high-resolution evaluation of EM interactions involving microscopic probes in MRI environments, supporting simulations that are otherwise impractical with full-wave MP modeling. Significance: HB provides a reliable framework for preclinical safety assessment and design optimization of graphene-based implants, facilitating accelerated translation of microscopic implant simulations toward human-scale applications in the future.

Abstract

Objective: Implementing electrophysiological recordings within an MRI environment is challenging due to complex interactions between recording probes and MRI-generated fields, which can affect both safety and data quality. This study aims to develop and evaluate a hybrid electromagnetic (EM) simulation framework for efficient and accurate assessment of such interactions. Methods: A hybrid EM strategy integrating the Huygens’ Box (HB) method with sub-gridding was implemented in an FDTD solver (Sim4Life). RF coil models for mouse and rat head were simulated with and without intracortical (IC) and epicortical (EC) graphene-based micro-transistor arrays. Three-dimensional multi-layered probe models were reconstructed from two-dimensional layouts, and transmit field (B₁⁺), electric field (E), and specific absorption rate (SAR) distributions were evaluated. Performance was benchmarked against conventional full-wave multi-port (MP) simulations using Bland–Altman analysis and voxel-wise percentage differences. Results: HB simulations reduced computational time by approximately 70–80%, while preserving spatial patterns of |B₁⁺|, |E|, and SAR, including transmit-field symmetry and localized high-field regions. Deviations from MP were minimal for |B₁⁺| (median Δ% 0.02–0.07% in mice, −3.7% to −1.7% in rats) and modest for |E| and SAR, with absolute SAR values remaining well below human safety limits. Graphene-based arrays produced negligible effects on RF transmission and SAR deposition. Conclusion: The HB approach enables computationally efficient, high-resolution evaluation of EM interactions involving microscopic probes in MRI environments, supporting simulations that are otherwise impractical with full-wave MP modeling. Significance: HB provides a reliable framework for preclinical safety assessment and design optimization of graphene-based implants, facilitating accelerated translation of microscopic implant simulations toward human-scale applications in the future.