BESA MRI

BESA MRI is a CE-certified software to coregister EEG / MEG data with individual MRI data. BESA MRI is the first software that offers an easy, intuitive interface with an integrated workflow guiding the user step-by-step.

MRI data import is easily performed with an automated DICOM reader. MRI data are transformed into Talairach space after only few quick and easy work steps. 3D positions can be defined intuitively by clicking and dragging visualized MRI data.

The high quality of cortex and scalp reconstruction is unrivalled as it is based on an automated, robust inhomogeneity correction. Segmentation procedures are automated employing advanced algorithms developed by BESA.

BESA MRI runs in combination with BESA Research 5.3.7. EEG / MEG data can be coregistered with individual MRI data using individually digitized electrode positions or headshape points. As a unique feature of BESA MRI, 10-10 standard electrodes (including inferior electrodes) can also be morphed with individual MRI data. Coregistered electrode coordinates are immediately available in BESA Research. Thus, source images / localizations can be displayed on the individual MRI even if no individual digitization of electrodes has taken place.

Integrated workflow for all user-interactions

BESA MRI was designed to be maximally user-friendly and intuitive. All steps that require user-interactions are guided by a workflow, prompting the user to perform the next step and providing integrated context-related help, which can be turned off if desired.

A workflow consists of a series of worksteps that have to be done to finalize a project. Each workstep realizes a set of user interactions needed to achieve the workstep-specific result. Some worksteps can be run in automated processing mode with preset parameters, e.g. inhomogeneity correction and segmentation. Thus, only a few user interactions are needed during the initial worksteps.

Automatic preprocessing with inhomogeneity correction

BESA MRI automatically corrects for hardware-related gray-value fluctuations of MRI images. Inhomogeneity correction is needed as a major workstep prior to the segmentation of different brain tissues. In BESA MRI, this correction is done by an automated workstep realized as an iterative procedure based on the Adaptive Fuzzy C-Means (AFCM) algorithm (Pham, D. and Prince, J. (1999)) enhanced by incorporating anatomical template masks. Without inhomogeneity correction the correct segmentation of cortical surfaces cannot be guaranteed. Therefore, BESA MRI provides an unrivalled quality of scalp and cortex reconstructions.

Automatic reconstruction of scalp and cortex

After inhomogeneity correction the scalp and cortex of the subject are automatically segmented. The reconstruction of the scalp surface is done by segmenting the subject's head from the background using a level set algorithm. Optimal results are achieved in an iterative process. Cortex segmentation is based on a white matter classification. The result is carefully smoothed and inflated to generate the cortical surface. This surface can be used as an approximate source space for cortical source imaging.

Coregistration using digitized electrodes / headshape points or 10-10 / 10-20 standard electrodes

MRI data can easily be coregistered with EEG / MEG data using individually digitized electrode positions or headshape points. However, as a unique feature of BESA, EEG data can also be coregistered with individual MRI data by using standard electrode sets (10-10 or 10-20 system as well as other standard EEG caps) available in BESA Research 3.5.7 if no individual digitization was performed. BESA MRI was developed to optimally interact with BESA Research 3.5.7. All relevant files are automatically synchronized between BESA MRI and BESA Research guaranteeing maximal user-friendliness.

Overlay of source reconstructions on the individual MRI

Source localizations performed in BESA Research can be instantly projected onto the individual anatomy of the subject within the source analysis module of BESA Research 3.5.7 by right-clicking into the solution-frame of the source analysis window and choosing ‘Display MRI’ or typing ‘A’ (anatomy). Discrete source solutions and distributed source solutions can be displayed at the same time. Topographical maps can be projected on the individual scalp reconstruction of the subject.

System requirements

• Windows® 7, Vista or XP Service Pack 2
• Processor: minimum: 2 GHzRAM: minimum: 2 GB
• Display resolution: minimum: 1280x800 pixels
• Graphics card supporting OpenGL 1.1 with 16 MB RAM or more

Certification

BESA MRI has CE certification