Format

Send to

Choose Destination
Brain Stimul. 2015 Sep-Oct;8(5):965-73. doi: 10.1016/j.brs.2015.05.008. Epub 2015 May 29.

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

Author information

1
Faculty of Arts and Sciences, University of Toronto, Canada.
2
Berenson-Allen Center for Noninvasive Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA; Bioengineering and Telemedicine Centre, ETSI Telecomunicación, Universidad Politécnica de Madrid, Spain.
3
Berenson-Allen Center for Noninvasive Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
4
Berenson-Allen Center for Noninvasive Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA; Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA; Athinoula A. Martinos Center for Biomedical Imaging, Harvard Medical School, Boston, MA, USA.
5
Department of Psychiatry, University of Toronto, Canada; MRI-Guided rTMS Clinic, University Health Network, Toronto, Canada.
6
Institute of Medical Science, University of Toronto, Canada; Department of Psychiatry, University of Toronto, Canada; Temerty Centre for Therapeutic Brain Intervention at the Centre for Addiction and Mental Health, Toronto, Ontario, Canada.
7
Institute of Medical Science, University of Toronto, Canada; Department of Psychiatry, University of Toronto, Canada; MRI-Guided rTMS Clinic, University Health Network, Toronto, Canada. Electronic address: jonathan.downar@uhn.ca.

Abstract

BACKGROUND:

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.

OBJECTIVE:

To quantify the discrepancy in scalp site between BeamF3 versus MRI-guided neuronavigation for left DLPFC.

METHODS:

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.

RESULTS:

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.

CONCLUSIONS:

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.

KEYWORDS:

Magnetic resonance imaging; Neuronavigation; Prefrontal cortex; Scalp; Transcranial magnetic stimulation

PMID:
26115776
PMCID:
PMC4833442
DOI:
10.1016/j.brs.2015.05.008
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center