title: Concordance Between BeamF3 and MRI-neuronavigated Target Sites for Repetitive Transcranial Magnetic Stimulation of the Left Dorsolateral Prefrontal Cortex.
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.
authors.affiliation: Faculty of Arts and Sciences, University of Toronto, Canada.
authors.forename: Arsalan
authors.initials: A
authors.lastname: Mir-Moghtadaei
authors.affiliation: 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.
authors.forename: Ruth
authors.initials: R
authors.lastname: Caballero
authors.affiliation: Berenson-Allen Center for Noninvasive Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Fried
authors.affiliation: 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.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Fox
authors.affiliation: Faculty of Arts and Sciences, University of Toronto, Canada.
authors.forename: Katherine
authors.initials: K
authors.lastname: Lee
authors.affiliation: Department of Psychiatry, University of Toronto, Canada; MRI-Guided rTMS Clinic, University Health Network, Toronto, Canada.
authors.forename: Peter
authors.initials: P
authors.lastname: Giacobbe
authors.affiliation: 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.
authors.forename: Zafiris J
authors.initials: ZJ
authors.lastname: Daskalakis
authors.affiliation: 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.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Blumberger
authors.affiliation: 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.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Downar
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D038361:Neuronavigation / Q000379:methods*; D017397:Prefrontal Cortex / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods*
keywords: Magnetic resonance imaging; Neuronavigation; Prefrontal cortex; Scalp; Transcranial magnetic stimulation