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faq:how_change_mri_orientation_size_fov [2013/05/23 12:59]
144.82.46.254 [How to change the MRI orientation, the voxel size or the field-of-view?]
faq:how_change_mri_orientation_size_fov [2017/08/17 11:21] (current)
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 //Figure 1. Anatomical mri plotted **without** using ft_volumereslice before plotting// //Figure 1. Anatomical mri plotted **without** using ft_volumereslice before plotting//
  
-When you call the **[[reference:​ft_volumereslice]]** function on the anatomical MRI, it will apply the transformation matrix to the field **anatomy** and interpolate the anatomical data onto a new voxel-grid that is aligned with the axis of the head coordinate system. ​By default it will output ​the MRI volume with the same number ​of voxels and resolution. The output will have  a different orientation of the anatomy and consequently,​ a different transformation matrix. ​+When you call the **[[reference:​ft_volumereslice]]** function on the anatomical MRI, it will apply the transformation matrix to the field **anatomy** and interpolate the anatomical data onto a new voxel-grid that is aligned with the axis of the head coordinate system. ​If the input MRI has a coordsys field, the center of the volume ​will be shifted (with respect to the origin ​of the coordinate system) for the brain to fit nicely in the box. By default the voxel resolution ​is 1 mm. The output will have a different orientation of the anatomy and consequently,​ a different transformation matrix. ​
  
 Plotting the resliced anatomical MRI results in a figure with the usually desired orientation of the head (Figure 2). Plotting the resliced anatomical MRI results in a figure with the usually desired orientation of the head (Figure 2).
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 Isotropic voxels are necessary if we want to apply morphological operators to the anatomical volume (e.g. dilating, opening, etc.). These operations occur for example when the skull tissue is segmented in an anatomical volume (e.g. see [[development:​headmodel_tutorial_eeg|this tutorial]]). ​ Isotropic voxels are necessary if we want to apply morphological operators to the anatomical volume (e.g. dilating, opening, etc.). These operations occur for example when the skull tissue is segmented in an anatomical volume (e.g. see [[development:​headmodel_tutorial_eeg|this tutorial]]). ​
  
-==== Change the field-of-view (VOF) ====+==== Change the field-of-view (FOV) ====
  
 The **[[reference:​ft_volumereslice]]** function is also able to change the number of voxels along each direction. This can be useful for example, when the preprocessing of the anatomical images requires a specific image size (e.g. see [[tutorial:​minimumnormestimate|this tutorial]]). The **[[reference:​ft_volumereslice]]** function is also able to change the number of voxels along each direction. This can be useful for example, when the preprocessing of the anatomical images requires a specific image size (e.g. see [[tutorial:​minimumnormestimate|this tutorial]]).
  
-In the figures above you can appreciate the change in the VOF by considering the MRI in the original representation not being in the centre of the picture, whereas after reslicing it is in the centre and better fills the available space.+In the figures above you can appreciate the change in the FOV by considering the MRI in the original representation not being in the centre of the picture, whereas after reslicing it is in the centre and better fills the available space.