MRI-free neuronavigation for transcranial magnetic stimulation in severe depression

This paper presents a MRI-free neuronavigation technique for repetitive transcranial magnetic stimulation (rTMS). This method is composed of three steps: 1) surface sampling of the subject’s scalp and face thanks to a 3D tracker, followed by Poisson surface reconstruction, 2) non-linear surface registration of an atlas surface to the extracted surface using an efficient modified non-linear EM-ICP algorithm [2], and 3) extrapolation of the transformation to a cortical stimulation target. Results have been obtained on a database of 10 subjects and have shown an accuracy of 10.2 mm. Although clearly less accurate than neuronavigation on the subject’s MRI, we advocate that this neuronavigation method is reproducible and acceptable for routine application of rTMS in severe depression.