by Dr. Tracy Warbrick and Dr. Michael Schubert
Application Specialist EEG-fMRI and Product Manager (Brain Products)
We are excited to let you know that Carbon Wire Loops (CWL) for the BrainCap MR are now available to order.
Why Carbon Wire Loops?
For EEG data acquired during fMRI scanning the gradient artifact and cardioballistic artifact are corrected using an average template subtraction approach. This relies on an artifact signal that repeats regularly; for gradient artifact it is the imaging volume that repeats over time and for cardioballistic artifact it is the cardiac cycle. Motion-related artifacts, on the other hand, are non-cyclic and unpredictable. Therefore, we need to consider a different approach.
Movement-induced signals can be measured by a loop moving inside a magnetic field (Faraday’s law of induction). As such, CWLs attached to the BrainCap MR can be used for obtaining reference signals inside the MRI scanner. The small movements of these CWLs in the magnetic field generate signals that can then be used to estimate and remove motion artifacts from the EEG.
Compared to our pre-announcement earlier this year, we made some small changes to the CWLs during our final testing phase to optimise the CWL signal. The solution now contains 4 larger loops situated at frontal-left, frontal-right, parietal-left, and parietal-right locations. The CWLs can be included on any of our standard BrainCap MRs and can be used in MRI scanners up to 3 T (subject to our general 3 T EEG-fMRI conditions for use). Because the loops are bipolar, a BrainAmp ExG MR amplifier will be needed to record these signals. If you already have a BrainAmp ExG MR you can of course use it for CWL measurements. However, if you would like to measure other signals at the same time, e.g. EMG or GSR, you will need a second BrainAmp ExG MR: one for the CWL measurements (positioned at the head end of the scanner) and one for the peripheral physiology measurements (positioned at the foot end of the scanner).
Our CWL solution provides you with the hardware necessary
to use CWLs in the MR environment easily and safely
We work closely with the research community when developing new products and our cooperation partners provide valuable input to this process. Our CWL solution was developed as part of an ongoing collaboration with The Florey Institute of Neuroscience and Mental Health, Melbourne, Australia. Additionally, this group have published some MATLAB® code that can be used to process the CWL data (Abbott et al., 2015).
Researchers have also been working independently on data handling methods and there is an EEGLAB Toolbox available for processing CWL data (van der Meer et al., 2016). Furthermore, the author of this Toolbox, Dr. Johan van der Meer, gave us an excellent introduction to this analysis method in our recent CWL webinar.
Some of our customers have already been using CWLs in their research and are happy to share their experience with you. Professor Jean Gotman’s lab at the Montreal Neurological Institute, McGill University, have been using CWLs for several years and have provided input to the development of our solutions. Professor Gotman and his colleagues Nicolas von Ellenrieder, Andreas Koupparis, and Natalja Zazubovits have written a user experience article that can be found in this issue of the Press Release.
Dr Lars Hausfeld (Department of Cognitive Neuroscience, Maastricht University) has been involved in testing our CWL solution in the field and has provided an overview of his experience with handling the data.
Our CWLs for the BrainCap MR will help you take your MR-related artifact handling to the next level. Please feel free to contact us (via email, contact form or chat) or your local distributor if you would like further information on Carbon Wire Loops for the BrainCap MR.
Abbott DF, Masterton RAJ, Archer JS, Fleming SW, Warren AEL, Jackson GD.
Constructing carbon fiber motion-detection loops for simultaneous EEG–fMRI.
Frontiers in Neurology 5(260)1- 16 (2015) (doi: 10.3389/fneur.2014.00260 ).
v. d. Meer JN, Pampel A, Van Someren EJW, Ramautar JR, van der Werf YD, Gomez-Herrero G, et al.
Carbon-wire loop based artifact correction outperforms post-processing EEG/fMRI corrections – A validation of a real-time simultaneous EEG/fMRI correction method.
NeuroImage. 2016 Jan 15;125:880–94.