This model is intended to calculate the parameters of a 1-tissue compartment model. It is just a slightly modified version of the classical implementation of Alpert's time-weighted integral approach for brain perfusion.
There are two changes:
1.The parameters are expressed as K1, k2, and Vt (rather than f, f/p, p).
2.Whole blood activity can be subtracted for spillover correction.
Acquisition and Data Requirements
Image Data |
A dynamic PET data set. |
Blood Data |
Input curve from the time of injection until the end of the acquisition. |
Blood-related TAC |
Optional. The delay and dispersion fit can be applied for brain perfusion data with [15O]-H2O scans. |
Blood Preprocessing
The same blood Preprocessing steps are available as for the brain perfusion model, but except for the data definition field all options are initially disabled as shown below.
If no whole-blood TAC is defined, the plasma curve will be used for spillover correction.
Model Preprocessing
During model Preprocessing a look-up table is calculated within a range of k2 values. The specifications include an optional TAC which is interpreted as whole-blood activity to be subtracted from the pixelwise TACs.
vB |
Blood volume fraction defining the pixelwise blood spillover correction. The corrected TACs before estimation of k2 are calculated by |
ntab |
Number of pre-calculated values in the look-up table. Should be an even number. |
k2 |
Efflux rate constant. The lower and upper limit of tabulation must be entered in the k2 restriction fields. |
Percent masked pixels |
Exclude the specified percentage of pixels based on histogram analysis of integrated signal energy. Not applied in the presence of a defined mask. |
Model Configuration
K1 |
K1 rate constant of 1-tissue compartment model. |
k2 |
k2 rate constant of 1-tissue compartment model. |
Vt |
Distribution volume. |