Task 1, Performing a semimanual transformation on datasets to the Talairach coordinate system

Task 1, Performing a semimanual transformation on datasets to the Talairach coordinate system

Transforming, or converting, datasets into Talairach space provides scientists with the ability to identify important structures within the standard brain. The Talairach atlas is as much a reference system as it is a coordinate system.

The main steps involved in transforming a dataset into the Talairach coordinate system are:

1 Performing anterior commissure and posterior commissure (AC-PC) alignment on [TechGuide_MappingBrainsTalairach.html#1221097 page 12]

2 Transform the AC-PC image to Talairach alignment on [TechGuide_MappingBrainsTalairach.html#1221581 page 29]

Performing AC-PC alignment

In the Talairach system the anterior commissure is often referred as the "origin," because it is the origin of the Talairach grid. In this first semimanual task, you need to identify and set five separate landmark points, beginning with the anterior commissure. Setting these points aligns the anterior commissure and posterior commissure that forms the basis of the Talairach grid. The landmark points, shown in [TechGuide_MappingBrainsTalairach.html#1291062 Figure 26], are:

AC superior edge-Top middle of anterior commissure

AC posterior margin-Rear middle of posterior commissure

PC inferior edge-Bottom middle of posterior commissure

First midsagittal point-Some point in the midsagittal plane; abbreviated as SG1

Another midsagittal point-Some other point in the midsagittal plane; abbreviated as SG2

When you've set these points, the Talairach grid is formed from these axes (refer to [TechGuide_MappingBrainsTalairach.html#1221132 Figure 19]):

Y axis-Anterior commissure and posterior commissure.

Z axis-The longitudinal (interhemispheric or midsagittal) fissure is aligned to the yz plane, thus defining the z axis.

X axis-The right-left axis perpendicular to the y and z axes.

Figure 19. The x, y, and z planes in an image after AC-PC alignment

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