Elastic Deformation Workflow

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Elastic Deformation Workflow

The deformable registration approach is the template-based normalization of SPM8 mainly suited for the stereotactic normalization of brain images using appropriate template images which can be loaded with the picture_7565 button. However, application to different scenarios is also possible.

Please first load the input images on the LOAD INPUT IMAGES sub-page. To proceed select the Deformable registration as Matching method.

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On the REFERENCE & MATCHING sub-page make sure the Species setting is correct and load the reference image either with REF: Load, or using the shortcut picture_7565 to load an in-built template. Note that the selection of built-in templates changes according to the species selection.

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Deformable Matching Parameters

The Deformable matching algorithm uses several parameters, which are hidden from the user interface. For the HUMAN species there are two presets, picture_7573 for the normalization of CT brain images, and picture_7553 otherwise. The red bar above the buttons indicates which preset is active. For other species, the CT preset is absent.

To enable a preset and edit the parameters please select one of the buttons. A dialog window opens and shows the current configuration. The HUMAN default settings are shown below and can always be restored with the Set Default button.

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Note the Apply CT scaling options which transform the values in the CT image such that the contrast between bone and soft tissue is reduced and they are more similar to the usual anatomical images. The parameter details and the deformation method are described in a separate section.

Important: The parameter settings are serialized. The next time Deformable matching is selected for the same species, the last parameter configuration will be applied. This is particularly relevant for the Matching without Interaction functionality.

Resampling Parameters

With Deformable matching, an additional reslicing option appears in the status line.

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Concentration is the standard setting and means, that the image pixel values are interpolated such that the concentration of the pixel values in a region is maintained. With Total Amount, however, the pixel values are "volume modulated" such that the region average times the region volume remains constant. Images resampled with Total Amount setting can be used for "voxel based morphometry".

Starting the Registration

Please use the Match Current button to start the registration of the currently selected INP series to the REF series. In the case of multiple INP series the picture_7372 is also active. It allows matching each INP series to the REF applying the same registration parameters.