MRI-free Virtual Neuronavigation for TMS

Abstract

Methods to determine coil position are paramount in TMS. Existing approaches are limited to scalp heuristics or depend on some combination of neuronavigation hardware, average brain templates, as well as subject MRI and/or evoked responses. We developed head-model guided TMS virtual neuronavigation without subject MRI, specialized hardware, or evoked responses. The MRI-free virtual neuronavigation involves three scalp measurements which are then used to generate an individualized head model by applying ellipsoid-based affine transformations to the MNI standard head model. Virtual neuronavigation is then performed on this individualized head model for any brain target. The coil position is then provided to the operator in simple geodesic measurements. We simulated this process on MRI data of fifteen subjects showing a mean error of 2.75 mm, outperforming the accuracy of scalp heuristic targeting approaches.