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Updated: May 15, 2025
Individualized rTMS Treatment for Depression using an fMRI-Based Targeting Method
Published on: August 2, 2021
Personalized models of Beam/F3 targeting in transcranial magnetic stimulation for depression: Implications for
Divya Rajasekharan1, Michelle R Madore1, Paul Holtzheimer2
1Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, 401 Quarry Rd, Stanford, CA 94305, USA; Mental Illness Research, Education and Clinical Center, VA Palo Alto Health Care System, 3801 Miranda Ave, Palo Alto, CA 94304, USA.
Background:
Clinical transcranial magnetic stimulation (TMS) for depression routinely relies on the scalp-based Beam/F3 targeting method to identify stimulation targets in the dorsolateral prefrontal cortex (dLPFC). Scalp-based targeting offers a low-cost and easily implemented method for TMS coil placement, enhancing treatment availability. However, limited anatomical and functional specificity of the Beam/F3 method may affect treatment outcomes, motivating assessment of the clinical standard.
Methods:
In a naturalistic clinical trial of TMS conduced at four Veterans Affairs hospitals, the authors evaluate the Beam/F3 method using neuroimaging incorporated before TMS, after five treatment sessions, and after all thirty sessions. Personalized anatomical and electric field (E-field) models were developed to assess target location and network engagement, as well as subsequent effects on clinical outcomes.
Results:
Anatomical models demonstrate that the Beam/F3 method produced reliable targets in the dLPFC across individuals and repeated treatment sessions. E-field models revealed that baseline anticorrelation between the stimulation center and the sgACC was associated with antidepressant symptom response after five TMS sessions (p=0.032,r2=0.100,N=46) and at the end of treatment (p=0.042,r2=0.107,N=39). Relatedly, E-field magnitude at the sgACC-anticorrelated peak in the prefrontal cortex correlated with symptom response throughout treatment (early treatment: p=0.001,r2=0.220,N=46; end of treatment: p=0.026,r2=0.127,N=39).
Conclusions:
This work establishes that scalp-based targeting can produce reliable targets in the dLPFC and be successfully evaluated using a combination of neuroimaging and E-field modeling in pragmatic, multisite applications. Importantly, this investigation also found that significant network effects occur early in treatment and that Beam/F3 targets can engage functional mechanisms in TMS.
