PXMOD Implementation

Acquisition and Data Requirements

Image Data

A dynamic PET data set.

Blood Data

The plasma activity from the time of injection until the end of the acquisition.

Optionally: whole blood activity to be subtracted from the pixel-wise TACs, loaded as Whole Blood Data in Blood Pre-processing.

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.

PXMOD Alpert General Blood Pre-Processing

If no whole-blood TAC is defined, the plasma curve will be used for spillover correction.

Model Preprocessing

During model Preprocessing a lookup 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 pixel-wise TACs.

PXMOD Alpert General Model Pre-Processing

vB	Blood volume fraction defining the pixel-wise blood spillover correction. The corrected TACs before estimation of k₂ are calculated by TAC_corr = (TAC - vB*C_BloodTot)/(1-vB)
ntab	Number of pre-calculated values in the lookup 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.
Threshold	Discrimination threshold for background masking.

Map Parameters

PXMOD Alpert General Model Parameters

K1	K₁rate constant of 1-tissue compartment model.
k2	k₂ rate constant of 1-tissue compartment model.
Vt	Distribution volume.