Repetitive transcranial magnetic stimulation (rTMS) is a tool that can be used to administer treatment to neuropsychiatric disorders such as major depressive disorder (MDD). Though, the clinical efficacy is still rather modest. Overly general stimulation protocols that neither consider patient-specific depression symptomology nor individualized brain characteristics, such as anatomy, or structural and functional connections, may be the cause of the high inter- and intra-individual variability in rTMS clinical responses. Multimodal neuroimaging can provide the necessary insights into individual brain characteristics and can therefore be used to personalize rTMS parameters. Optimal coil positioning should include a three-step process: 1) identify the optimal (indirect) target area based on the exact symptom pattern of the patient; 2) derive the cortical (direct) target location based on functional and/or structural connectomes derived from functional and diffusion MRI data; 3) determine the ideal coil position by computational modeling, such that the electric field distribution overlaps with the cortical target. These TMS-induced electric field simulations, derived from anatomical and diffusion MRI data, can be further applied to compute optimal stimulation intensities. Besides MRI, EEG can provide complementary information regarding the ongoing brain oscillations. This information can be used to determine the optimal timing and frequency of the stimuli. The heightened benefits of these personalized stimulation approaches are logically reasoned, but speculative. Randomized clinical trials will be required to compare clinical responses from standard rTMS protocols to personalized protocols. Ultimately, an optimized clinical response may result from precision protocols derived from combinations of personalized stimulation parameters.
Copyright © 2021. Published by Elsevier Inc.