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Brain VOI Editing and Statistics Calculation

The result of structure outlining is shown on the VOIS page.

The image display shows a fusion of the MR image with the averaged PET image in the selected Result space. Please use the fusion slider to change the weight between the image contributions, and use the individual image control tabs for the changing the individual image displays. The example below shows the contour VOIs with 50% mixing and MR only.

VOI Editing and Selection

At this time the contour VOIs can be interactively adjusted using the VOI features of PMOD, which are described in the PMOD Base Functionality Guide. Note that the List tab should be selected for the adjustment, and that depending on the configuration only a reduced set of VOI tools may be available.

A subset of the VOIs can easily be selected on the Group tab as described above.

Quality Control

The QC box enabled allows previewing the VOIs overlayed on the selected functional image based on the capture settings. This setting is saved in the protocol and is relevant for the batch processing: it allows at the end of the batch processing to quickly inspect the outcome of the matching procedures in the selected result space.

Partial-Volume Correction (PVC)

The PNEURO tool supports the GTM-based partial-volume correction (PVC) of the PET signal. Note that the corrections are sensitive to the S/N ratio and might produce large artifacts for noisy dynamic data.

The PVC selection has five choices:

For the purpose of VOI-based PVC methods, the VOIs complementary to the gray matter masked VOIs as well as a VOI with all CSF pixels are taken into account. This strategy will be applied, even if some VOIs were deleted by the user.

If a PVC method is used, both the original and the corrected statistics are calculated. Note that due to the high number of VOIs the PVC calculation may take several minutes and consumes a significant amount of RAM.

PVC-corrected Images

Note that the PVC-corrected images are available for inspection after the Statistics calculation. When returning to the VOIS page, the inspection button to the right of the PVC method indicated below has become active. It opens the corrected images in a dialog window where they can be interactively inspected and saved.

Statistics Calculation

Once the VOIs are acceptable, it is recommended to first save them and then proceed with statistics calculation by the Statistics action button. The result (of the selected VOIs only) is shown on the separate Statistics page of the PNEURO tool, from where it can be further evaluated.

Parametric Mapping

If the PET images are dynamic and the PXMOD option is included in the license, parametric mapping using pixel-wise models can be directly applied within PNEURO, as described in a separate section.

Normal Database Comparison

As PNEURO is able to provide the PET images normalized to the atlas space, there is a direct link with the Brain Norm Functionality. The Compare button copies the PET images as they appear on the VOIs page to the Compare To Norm page where they can be compared against a normal uptake pattern of a normal database. Conveniently, if the two spaces match, there is no need to perform a normalization.