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Model selection & Preprocessing

Contents

How do I obtain the kinetic parameters and the fitted TAC for a region of interest?

A PET dynamic study must be loaded (see the Load Data help section), together with a mask or a set of TACs, to begin the kinetic analysis process. After that, the Model selection and Preprocessing frame changes into blue, and the kinetic model can be chosen. Then, you have to press the Preprocess Model button, and a new configuration window appears, where the preprocessing parameters for the selected model can be specified. In this window there is also a new Preprocess Model button. The calculation starts when you click on it. The fitted and input TACs are shown in the Plots frame for comparison, and the kinetic parameters are presented in the Results frame.

Which input parameters do I need to specify to perform the fitting?

The input parameters are selected in the configuration window, which opens when the user clicks on the Preprocess Model button. Each kinetic model requires different input parameters to be specified. You can see the information for each model by clicking on the help icon or in the following links: SRTM model, Carson model, PatlakRef model or LoganPlot model.

Can I perform more than one fit, to try different input parameters?

Yes. After the fitting curve and the estimated parameters are shown, you can restore the minimized configuration window to choose another parameter combination. When the fit is considered correct, the configuration window can be closed py pressing the OK button. The parameters used / obtained for that particular configuration will be used in the subsequent processing steps. If a new preprocessing fit is later needed, it can be performed by clicking on Preprocess Model in the main frame again.

Can I see and/or save the values of TACs?

Yes, you just need to right-click on any point of the Plots frame. Two options are available: saving the plots (Save plots) or showing the numerical values of the curves (View values). If Save plots is chosen, the software will ask for a file name, a format and a save directory. If View values is selected, a new window will open, showing the values. The values in this window can be saved by clicking on the Save values button.

Can I see the measured TAC of any region again after performing a new fit?

Yes. Two radio buttons will be enabled in the Plots frame after any fit. They allow switching between the display of the fitted curve with its associated TACs, and the display of any pair of measured TACs (Show TAC's), specified as region of interest and reference region.

Can I restore a preprocessing perfomed for a given model at any time?

Yes, but only for the last preprocessing. If you have done a preprocessing for a given model, you just need to select that model in the Model selection & Preprocessing frame and the results of last preprocessing will be loaded.

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