• Object ID: 00000018WIA30585970GYZ
  • Topic ID: id_40021838 Version: 1.3
  • Date: May 23, 2022 3:33:46 AM

Adjust the Voxel shift

About this task

Use these steps to move the spectroscopy grid so that a CSI voxel is positioned over an area of interest (e.g., over pathology). Voxel shifting allows you to adjust the position of the encoded voxels (determined by the CSI Grid) relative to the anatomy. This procedure can also be used to move the grid so the CSI voxel of interest is not a partial volume; that is, align the grid with the posterior edge of the PROSE voxel.

Important: For oblique (or non-oblique) spectroscopy acquisitions, the grid offset location is displayed at the bottom of the upper-left viewport.

Step-by-step instructions

  1. From the spectroscopy Review Steps, click Metabolites.
    Figure 1. Metabolites Review Step


  2. If the Voxel Shifting tab does not automatically display, click the Tools icon and then the Voxel Shifting tab.
  3. From the Voxel Shifting tab, click the Grid icon to turn it on.
  4. Use the Arrow icons to move the grid in the direction the arrow is pointing to an area of interest.
    Figure 2. The new grid and the old grid are both visible


    Table 1. Image legend
    NumberDescription
    1New grid
    2Existing grid
  5. Click Compute. The blue grid disappears and the new red grid is in the position of the blue grid.
    • Repeat the move grid steps for voxel shift steps as many times as needed to adjust the grid location. Click Compute each time to calculate spectra at the new grid location.
    • Click Reset Shift to reset the voxel shift to the original location.
  6. Settings has three shifting algorithm options: none, sinc and linear. Kernel size can also be modified between 3 and 5. Click Save to save your modifications as the new default values.
    • Sinc is the closest approximation to the Fourier frequency shift algorithm.
    • Linear is a simple linear interpolation.
    • Kernel size defines how many adjacent voxels are used in the interpolation. The larger the number the more accurate the interpolation.

    Click Reset or Reset All to return to the original settings or factory settings. Click Save All to save changed selections as the new default values.