Concordance Between BeamF3 and MRI-neuronavigated Target Sites for Repetitive Transcranial Magnetic Stimulation of the Left Dorsolateral Prefrontal Cortex

• Published in: Brain stimulation Vol. 8; no. 5; pp. 965 - 973
• Main Authors: Mir-Moghtadaei, Arsalan, Caballero, Ruth, Fried, Peter, Fox, Michael D., Lee, Katherine, Giacobbe, Peter, Daskalakis, Zafiris J., Blumberger, Daniel M., Downar, Jonathan
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2015
• Subjects: Adolescent; Adult; Algorithms; Female; Humans; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Male; Middle Aged; Neurology; Neuronavigation; Neuronavigation - methods; Prefrontal cortex; Prefrontal Cortex - physiology; Scalp; Transcranial magnetic stimulation; Transcranial Magnetic Stimulation - methods; Transcranial magnetic stimulation; Prefrontal cortex; Magnetic resonance imaging; Scalp; Neuronavigation
• ISSN: 1935-861X; 1876-4754
• DOI: 10.1016/j.brs.2015.05.008

The dorsolateral prefrontal cortex (DLPFC) is a common target for repetitive transcranial magnetic stimulation (rTMS) in major depression, but the conventional “5 cm rule” misses DLPFC in >1/3 cases. Another heuristic, BeamF3, locates the F3 EEG site from scalp measurements. MRI-guided neuronavigation is more onerous, but can target a specific DLPFC stereotaxic coordinate directly. The concordance between these two approaches has not previously been assessed. To quantify the discrepancy in scalp site between BeamF3 versus MRI-guided neuronavigation for left DLPFC. Using 100 pre-treatment MRIs from subjects undergoing left DLPFC-rTMS, we localized the scalp site at minimum Euclidean distance from a target MNI coordinate (X − 38 Y + 44 Z + 26) derived from our previous work. We performed nasion-inion, tragus–tragus, and head-circumference measurements on the same subjects' MRIs, and applied the BeamF3 heuristic. We then compared the distance between BeamF3 and MRI-guided scalp sites. BeamF3-to-MRI-guided discrepancies were <0.65 cm in 50% of subjects, <0.99 cm in 75% of subjects, and <1.36 cm in 95% of subjects. The angle from midline to the scalp site did not differ significantly using MRI-guided versus BeamF3 methods. However, the length of the radial arc from vertex to target site was slightly but significantly longer (mean 0.35 cm) with MRI-guidance versus BeamF3. The BeamF3 heuristic may provide a reasonable approximation to MRI-guided neuronavigation for locating left DLPFC in a majority of subjects. A minor optimization of the heuristic may yield additional concordance. •Comparison of scalp versus MRI-based localization of DLPFC for rTMS treatment.•Data drawn from MRIs in 100 patients scheduled to undergo DLPFC-rTMS in a clinical trial.•BeamF3 algorithm had <6.5 mm discrepancy from MRI navigation in >50% of patients.•BeamF3 radial measurement fell significantly short of MRI coordinate by 3.5 mm.•Adjusted BeamF3 method may acceptably approximate neuronavigation if MRI unavailable.