Analysis of Induced Electric Field in Heterogeneous Head Models With the Consideration of Coil Configuration and Individual Difference in TMS

Transcranial magnetic stimulation (TMS) holds great promise for noninvasively diagnosing and treating neurological disorders. Based on the electromagnetic induction principle, the TMS coil’s alternating magnetic fields generate electric fields in targeted brain areas. However, the intricate and diverse brain structures across individuals pose challenges in predicting and enhancing the effectiveness of TMS treatments for a particular patient. In this study, computational modeling was utilized with fifty realistic, heterogeneous head models to investigate how individual differences influence the induced electric fields, focusing on their intensity and focality. The finite element method was applied to calculate the induced electric field in the brain. Seven commercially available TMS coils were placed at two anatomical locations: the vertex and the dorsolateral prefrontal cortex (DLPFC). The findings indicate that similar coil configurations produce consistent induced electric field strengths across subjects. More notably, this study examined the differences in induced electric field intensity among coils for each individual, rather than merely grouping subjects, underscoring the importance of individual variation. This research provides valuable reference and support for optimizing TMS device configurations and treatment protocols in practical clinical applications.