Population-optimized electrode montage approximates individualized optimization in transcranial temporal interference stimulation.

Background: Effective transcranial temporal interference stimulation (tTIS) requires an optimized electrode configuration to target deep brain structures accurately. While individualized electric field analysis using high-resolution structural MRI enables precise electrode placement, its clinical practicality is limited by significant costs associated with imaging, specialized software, and navigation systems. Alternatively, standardized electrode montages optimized through population-based electric field analysis might overcome these limitations, although it remains unclear how accurately this approach approximates individualized optimization.

Aim: This study evaluates the feasibility of using group-level electric field analysis to optimize the tTIS montage. Specifically, it seeks to maximize the intracranial electric field using a population-proxy approach and compare its efficacy to individualized electric field optimization.

Method: We optimize the montage across various populations, balancing the trade-off between focality and electric field strength at deep brain targets. The method is compared to conventional individualized electric field-based optimization. Factors such as population size and age were analyzed for their impact on montage selection and effectiveness.

Results: Population-based electric field optimization demonstrated comparable focality and targeting accuracy to individualized analysis, with a difference of up to 17 %. Age mismatch between the population proxy and the target individual reduced the focality of up to 8.3 % compared to an age-matched population proxy. Also, insufficient population size led to inconsistencies in montage optimization, although these were negligible for populations larger than 40 individuals.

Conclusion: This study demonstrates the capability of population-based electric field analysis to achieve targeting effects comparable to individualized-level electric field analysis in terms of focality and intensity. By eliminating the need for patient-specific MRI scans, this approach significantly enhances the accessibility and practicality of tTIS in diverse research and clinical applications.