Current Density Imaging during Transcranial Direct Current Stimulation using DT-MRI and MREIT: Algorithm Development and Numerical Simulation
Oh In Kwon, Saurav Z. K. Sajib, Igor Sersa, Tong In Oh, Woo Chul Jeong, Hyung Joong Kim, and Eung Je Woo
We developed an MR-based current density imaging technique to monitor the current flow inside the brain during tDCS (transcranial direct current stimulation). First, we create a subject-specific three-dimensional volume conductor model from the acquired anatomical MR images. Then, we incorporate into the model the directional information from a DT-MRI scan together with the measured magnetic flux density data subject to the externally injected stimulation current. A assuming an anisotropic conductivity distribution of the model, we compute a model-predicted current density and magnetic flux density distributions. By comparing the differences between the measured and computed magnetic flux density data, the proposed method iteratively updates the transversal components of the current density distribution produced by the stimulation current. We validated the novel current density imaging method using a realistic three-dimensional human head model, measured DT-MRI images, and simulated magnetic flux density data. We found that the method can reliably and quantitatively visualize internal current density distributions during tDCS treatments.
Keywords: MREIT, conductivity tensor, current density, diffusion tensor, magnetic flux density, tDCS