| ASA MRI review and head modeling |
| With ASA 4, we release a completely redesigned version of our MRI view. The new view is based on the latest technology available for rendering of pixelated images and 3D objects with optimal performance. The MRI view allows the free rotation of slices cut through the MRI. It combines the display of MRI, segmentation of head compartments, inverse reconstructions (such as MUSIC, LORETA, cortical imaging and cortical ERD/ERS, and dipole fit results), and fMRI. In addition, all objects usually shown in the 3D views (such as EEG/MEG maps, head models and sensors) can be added to the display. |
Talairach coordinate system and transformations The new ASA allows to transform results obtained for a individual into a standardized coordinate system based on the Talairach definition. For this purpose, a set of anatomical landmarks is placed in the subject's MRI, based on which the transofrmaton is carried out. The transformed MRI (which is quite different from the individual MRI, since orientation and spacing between MR slices are newly defined and applied to create a new block of MRI) is then exported in to ASA or Analyze (SPM) formats. The same export can be applied to LORETA and MUSIC results in order to obtain results that can be further processed in a group statistics. |  |
Nasion-ear markers The fiducials are now shown by colored markers in the MRI and can easily be reviewed in combination with the scalp surface. The fast rendering allows for rotation of the 3D image by mouse. |  |
Segmentation of MRI and CT The segmentation of the brain is used to create a head model for MEG reconstructions. In this figure, the brain rendering is shown in combination with the scalp segmentation (yellow regions) in 3D. |  |
Example of MUSIC source analysis The result of a MUSIC calculation, given an SEP average over 32 electrodes and an individual model of the subject's head, is displayed in combination with the scalp surface. The image shows the topology of the peak latency of 27 ms after stimulus by means of contour lines and the electrodes; the scalp surface is cut partly open. |  |