This article describes the capabilities of the BrainLoc program for 3D localization of sources of electrical activity (EEG) of the brain.
Introduction
Electroencephalography (EEG) is an accessible non-invasive method for studying the functional state of the brain. Based on EEG data, a doctor can make a conclusion about abnormalities in the functioning of the central nervous system. When diagnosing a disease such as epilepsy, electroencephalography and others LTM EEG video monitoring is the "gold standard". Using mathematical methods for processing EEG signals (dipole model method), three-dimensional localization of sources of paroxysmal epileptiform activity is available. This technique is widely used in modern clinical practice for lateralization and localization of the focus of epileptiform activity, for example, before surgical treatment.
Registration of brain evoked potentials (EP) is another method for diagnosing the functional state of the brain, in particular assessing cognitive function. Using the dipole model, it is possible to localize the sources of evoked responses. This technique is actively used in scientific research.
BrainLoc is not the only program that allows you to calculate the location of its source based on the EEG signal and EP. Alternative solutions are discussed below.
Purpose of the BrainLoc program
- Localization of sources of pathological electrical activity in epilepsy, trauma, stroke, tumors
- Localization of sources of evoked potentials, wave patterns, generators of rhythmic activity
Operating procedure
BrainLoc supports loading EEG signals from EDF and EDF+ files. However, below we will discuss how to work with BrainLoc using the example of integration with Neuron-Spectrum.NET software.
The EEG recording and analysis program Neuron-Spectrum.NET is tightly integrated with the BrainLoc program. When viewing an EEG signal in Neuron-Spectrum.NET software, just select the section of the traces with the mouse and use the context menu item “Export to BrainLoc”.
After this, the BrainLoc program is automatically launched and the EEG data is processed. In the program window that opens, you can view native EEG traces and the results of their mathematical processing in several views.
- Localization results on orthogonal head projections:
- Results of localization on tomographic sections of the brain and its three-dimensional model:
- Amplitude mapping:
- Assessment of the reliability of calculated parameters and automatic selection of reliable sources:
If a file with patient MRI data or a standard MRI file is connected to EEG processing, an additional MRI tab appears in the results area:
Some data, for example, amplitude mapping, is also available in the Neuron-Spectrum.NET software, but for a full analysis of the localization of sources of electrical activity in the brain, amplitude analysis of the scalp EEG alone is not enough.
By comparing the results of amplitude mapping in two programs, we can conclude that the EEG data export was correct. From the presented screenshots with the results of spike-wave amplitude mapping, it can be seen that in both programs the calculation results are the same and indicate the localization of the maximum spike amplitude under the F4 electrode.
Mathematical model of data analysis
BrainLoc uses two models for data analysis:
- Model with moving dipoles - for each moment in time of the analyzed data, its own dipole model is calculated, consisting of one or two moving dipoles, - you can set the time averaging window when calculating dipole sources.
- Model with stationary dipoles - a single model is calculated with the number of dipoles from one to eight for the entire selected piece of data, - model options:
a) dipole centers are tied to given structures,
b) search for the optimal location of dipole centers in the brain volume,
c) search for a constant optimal dipole orientation for the entire data fragment.
Reliability of the BrainLoc program
The BrainLoc program has undergone verification of its work results in leading medical research institutes and clinics in Russia:
- Institute of Neurosurgery named after. N.N.Burdenko RAMS
- Institute of Neurology of the Russian Academy of Medical Sciences
- Moscow Medical Academy named after. I.M.Sechenova
- Institute of Emergency Medicine named after. N.V. Sklifosovsky
- Institute of Psychiatry, Ministry of Health of the Russian Federation
- Neurosurgical Institute named after. A.L. Polenov and others
Publications with BrainLoc program
The BrainLoc program is used not only in clinical practice, but also in scientific research, both in Russia and other countries. Here are more than three hundred articles on which BrainLoc was used.
Here are some of them:
Video
Alternative solutions
As mentioned above, BrainLoc is not the only program of this kind. There are several foreign analogues that perform similar functions:
- LORETA - Low Resolution Brain Electromagnetic Tomography:
- AIT Encevis EpiSource - program for three-dimensional localization of pathological activity using EEG:
Both mentioned programs also have integration with Neuron-Spectrum.NET.
Useful materials
- Glossary of terms most commonly used by clinical electroencephalographers (Revision 2017).
- Video-EEG. Long-Term Monitoring.
- The ILAE classification of seizures and the epilepsies in the neonate.