Simpleware Case Study: Transcranial Direct Current Stimulation (tDCS)

Soterix Medical High-Definition transcranial Direct Current Stimulation using arrays of electrodes on the scalp

Overview

Transcranial direct current stimulation (tDCS) represents a neuromodulation technique that delivers a weak direct electrical current to the brain, and can be used to treat brain injuries, strokes, and other neural conditions. Soterix Medical and City College New York (CCNY) researchers use Simpleware software to develop tDCS solutions for neurological conditions, which are then implemented via neuromodulation technologies. ,, With tDCS, it is important to understand where the current is flowing, and how to optimize electrode placement to design treatment protocols, and to retrospectively analyze clinical outcomes.

Characteristics:

  • Synopsys Simpleware software used to segment and mesh MRI data of the head and brain
  • Simulation in COMSOL Multiphysics® reveals insights into effect of tDCS
  • Current work is exploring benefits of Soterix Medical HD-tDCS™ for stroke treatment

Thanks to

Soterix Medical, Inc and Department of Biomedical Engineering, The City College of New York, CUNY  

Marom Bikson • Abhishek Datta • Felipe Fregni • Jacek Dmochowski • Ole Seibt , Dennis Truong, Chris Thomas

“…my personal association with Simpleware goes back close to 15 years. The software makes it possible to create detailed models of the human head and simulate tDCS procedures, and have critically helped advance our modeling pipelines”

Abhishek Datta | Soterix Medical, Inc.

Introduction

The Soterix Medical team use a unique high-definition tDCS (HD-tDCS™) method that provides the same electrical current as standard tDCS, but uses smaller or multiple electrodes along with optimization algorithms and flow models to target and optimize treatment. Simpleware software has been a part of this process for almost 15 years, from early research at CCNY through to ongoing clinical trials and device optimization at Soterix Medical, with the long-term goal of improving and reducing risks for patients.

Image Processing and Mesh Generation

Soterix Medical workflows typically begin with Magnetic Resonance Imaging (MRI) scans from a healthy human head, before MATLAB and SPM are used to automatically segment the skin, bone, cerebrospinal fluid (CSF), and grey matter. The resulting files are imported to Simpleware ScanIP to carry out corrections of the original segmentation.

Segmentation and 3D editing of a human head from MRI using Simpleware ScanIP

Segmentation correction and 3D editing of the human head in Simpleware ScanIP

One of the common challenges for researchers is to remove unwanted features from the image data using 3D editing. This clean-up is time-consuming, and is tackled by using the Simpleware software mask statistics tool to sort connected regions by volume and remove any unnecessary data. Scripting is also used in Simpleware ScanIP to speed up the processing of importing files prior to segmentation.

Once segmented, the image data is meshed using the Simpleware FE Module to create a highly detailed model for simulation.

Simulation

Soterix Medical use COMSOL Multiphysics® to simulate current flow, taking into account stimulation electrode and other material properties to ensure a realistic representation of tDCS. Simulation must also consider factors such as skull thickness, the presence of sutures, eye cavities, and convoluted brain surface morphology, as well as CSF channels enclosing and perfusing the underlying cortex. Using these techniques, Soterix Medical can explore how tDCS affects individual patients.

FE simulation to determine optimal electrode configuration for tDCS

Determination of the optimal electrode configuration to use for a specific application. Comparison of different algorithms employed, resulting in 80% improvement in focality and 98% higher intensity at the target.

Impact

Soterix Medical are using Simpleware software to help build a modeling service for clinicians using MRI and fMRI scans to determine optical electrode placement and plan procedures. More recently, Soterix Medical have been involved in a clinical trial focused on stroke treatment, which explores how targeted electrical brain stimulation can help patients with chronic impairments, such as language impairment (aphasia) and particularly the loss of the ability to recall the names of everyday objects (anomia).

In this context, Soterix Medical have looked at brain damage and changes in cortical activation using unoptimized and optimized electrode placements. From this approach, a positive relationship has been identified between treatment-assistant increases in correct naming and modulation of areas in the left posterior and left anterior regions of the brain.

Current flow models comparing conventional-tDCS and Soterix Medical’s High-Definition-tDCS

Current flow models comparing conventional-tDCS and Soterix Medical’s High-Definition-tDCS

Based on early results, anomia treatment using HD-tDCS™ saw meaningful improvement outcomes compared to anomia treatment alone. The study is also looking at results from pre- and post-treatment fMRI (immediately after and six months later) to compare outcomes to a parallel study using conventional sponge-based (CS) tDCS. In future, Soterix Medical aim to automate the individualized modeling pipeline and provide this as a targeting service for clinicians.

Learn More

Watch Soterix Medical’s presentation on: Individualized Modeling for Stroke Patient Treatment Planning, recorded July 30, 2020.

Any Questions?

Do you have any questions about this case study or how to use Simpleware software for your own workflows?