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

Abstract

BackgroundThe 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.ObjectiveTo quantify the discrepancy in scalp site between BeamF3 versus MRI-guided neuronavigation for left DLPFC.MethodsUsing 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.ResultsBeamF3-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.ConclusionsThe 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.

Unilateral and bilateral MRI-targeted repetitive transcranial magnetic stimulation for treatment-resistant depression: a randomized controlled study

“…20,22,46 This finding also has important implications for clinical practice and suggests that MRI targeting and adjusting for coil-to-cortex distance is unlikely to yield higher remission rates than optimal methods of approximation and a stimulation intensity of 120% MT. 47,48 Future research to identify new methods to improve the efficacy of rTMS for TRD are needed. We propose that identifying and engaging biological targets of treatment response 49 may be a more productive method of enhancing efficacy.…”

Rostral anterior cingulate cortex is a structural correlate of repetitive TMS treatment response in depression

“…At BIDMC TMS was delivered using a NeuroStar TMS Therapy System (Neuronetics, Inc., Malvern, Pennsylvania) or Magstim Super Rapid stimulator (Magstim Company Ltd., UK) equipped with a 70-mm figure-of-eight coil and at Cornell TMS was delivered with the NeuroStar system. DLPFC targeting was 5.5 cm anterior to the motor cortex at BIDMC and via the beam F3 method at Cornell [11]. The number of rTMS sessions was 30–36 at BIDMC and 25 at Cornell.…”

Cortico-Striatal-Thalamic Loop Circuits of the Salience Network: A Central Pathway in Psychiatric Disease and Treatment

“…One of the most common targets for tDCS in the literature to date has been the dlPFC, often operationalized as EEG sites F3 and F4 in the standard 10–20 montage. The F3 site has been shown to correspond fairly closely to the dlPFC node appearing in the SN (Mir-Moghtadaei et al, 2015), suggesting that tDCS of F3 and F4 is anatomically positioned to stimulate the SN. Research studies and clinical trials of tDCS have targeted the dlPFC due to its hypothesized central role in executive function and cognitive control (Kuo and Nitsche, 2012).…”