Electrical Field Measurements & Simulations of TMS Coils

Electrical field measurements and simulations of the H7 and D-B80 coils: Non-equivalence of the TMS coils for obsessive compulsive disorder

Journal: Brain Stimulation 14 (2021) 1525e1527

Authors: Tzirini M, et al


In 2018, the FDA cleared deep transcranial magnetic stimulation (BrainsWay Deep TMS) with the H7 coil for obsessive-compulsive disorder (OCD) treatment following a double-blinded placebo-controlled multicenter trial.

Magventure’s D-B80 Coil was FDA-cleared in August 2020 to treat Obsessive-Compulsive Disorder (OCD), using the BrainsWay H7 Coil as a predicate device.  No RCT data has been reported using the D-B80 to date.


Compare the induced electric fields of the H7 Coil and D-B80 Coil in treatment position for OCD.


The study compared the induced electric field (EF) of the two coils in relevant brain regions (ACC and PFC) through 2 types of methods (22 distinct models in total):

    1. EF measurements of saline solution head model
    2. High-resolution electric field simulations of anatomical models


In all models, the H7 Coil was shown to stimulate 2-5 times greater brain volume than the D-B80 Coil in all the brain regions assessed.

The H7 Coil induces higher field intensities, whereas at the OCD treatment location, the effective field of the D-B80 is only induced in very shallow brain layers.

Many prefrontal structures which comprise the CSTC circuity (implicated in OCD) are stimulated by the H7 Coil, but not the D-B80 Coil.


Clinical efficacy in treating OCD demonstrated using the H7 Coil should not be assumed for the D-B80 Coil, given the distinct difference in induced electrical fields.

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