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In order to use parametric mapping in PKIN, the dynamic data have to be loaded in the PVIEW tool, VOIs outlined, and then the transfer to PKIN started as illustrated below. As PKIN can only handle a limited number of TACs, the default Maximal number of TACs is set to 10000, but can be changed.
Please select only the relevant VOIs in the list to the left. The VOI average TACs are shown in the curve area, with the number of included voxels indicated in brackets in the list to the right. Activate TAC of each VOI voxel, and then transfer the data with Send [SET] to create a new PKIN workspace, or Send [ADD] to use the selected PKIN workspace.
If no blood information is available for modeling, an average TAC from a reference VOI will be needed. It is recommended transferring it separately as an average TAC by calling the transfer window again, this time only selecting the reference VOI, enabling Averaged VOI TAC, enabling Append TAC data and finally activating Send [ADD].
Important: The image has to remain loaded in the PVIEW tool during parametric mapping in PKIN.
After the transfer from the PVIEW tool the voxel-wise TACs are arranged in the Region list labeled with the VOI name followed by the voxel coordinate in the image. As for average TACs, the blood and plasma data have to be loaded, or a reference approach used.
The whole PKIN functionality is then available for modeling. For instance, a few TACs can be averaged, a 1-tissue compartment model fitted as illustrated, propagated to all TACs using Copy to All Regions entry Model & Par, and fitted with Fit all regions.
Select the entry Create Parametric Maps in the Kinetic menu in order to generate parametric maps from model parameters. Note that this entry is only active when a voxel-wise TAC transfer from PVIEW has been performed.
The dialog window offers three methods on the Setup panel.
Create map from fitted PKIN models |
This method uses the results of the existing model fits in the PKIN workspace to generate the parametric maps. |
Fit PKIN TACs to create map |
This method is the same as above, but first a model fit is performed in all regions using the model configured in the selected region. |
Fit original image TACs to create map. |
This method is independent from the TAC contents in PKIN. It will use the model configured for the active region and fit it to the TACs of all voxels within the selected regions if Use only selected regions is enabled, and in the whole image volume otherwise. Note that the time required depends on the number of voxels to be fitted. |
The Generate button starts processing with the selected method, resulting in images on the tabs Parametric Maps, SE Maps and Model based Image. Note the synchronization between the images on the various panels and the Region selected in the PKIN interface as described below.