Van den Hoff et al. [1] have investigated and validated ^{11}C-acetate as a flow tracer. This methodology is implemented as the **Card Acetate (1 Compartment)** model. It employs a single tissue compartment model

with tracer exchange between arterial plasma C_{P}(t)_{ }and myocardial tissue C_{myo}(t).

Operational Model Curve

The differential equation C_{myo}(t) is given by

K_{1} is the product of flow F and extraction E

For acetate, the extraction is flow dependent [1]

Furthermore a metabolite correction is necessary to derive the plasma activity from whole blood measured in the left cavity [1]

with T_{1/2}=5.3 min. Including these relations into the differential equation yields

which is non-linear in F. The model curve incorporates a cardiac dual spillover correction, resulting in the operational equation

where

V_{LV} = spill-over fraction of the blood activity in the left ventricular cavity C_{LV}(t),

V_{RV} = spill-over fraction of the blood activity in the right ventricular cavity C_{RV}(t)

Implementation

When using the model from the PCARD module, the data are transferred appropriately. When using it in PKIN the blood data have to be loaded as follows:

- The left ventricle curve must be loaded as the
**Plasma activity**curve. No metabolite correction needs to be enabled on the**Blood**panel of PKIN because it is included in the tissue model. - The right ventricle curve must be loaded as the
**Whole blood**curve.

The following automatic adjustment is performed within the model:

- The spill-over fraction from the right ventricle V
_{RV}is automatically fixed to zero if the string "Sep" is*not*contained in the name a region. The assumption is that such a TAC is not from septal tissue and should thus be modeled with spill-over from the left ventricle only.

Parameter Fitting

The model includes the 4 fitable parameters **F**, **k2**, **vLV**, **vRV**. Please inspect the **%SE** standard error to get information about the reliability of the parameter estimates. The parameters for the correction of the flow-dependent extraction (**EF scale**, **EF exp**) and the metabolites (**MC scale**, **MC T12**) are initialized with the published values [1], but can be edited if needed. The **K1** parameter of the 1-tissue compartment model equivalent to the EF product is provided as s macro parameter.

Reference

1. van den Hoff J, Burchert W, Borner AR, Fricke H, Kuhnel G, Meyer GJ, Otto D, Weckesser E, Wolpers HG, Knapp WH: [1-(11)C]Acetate as a quantitative perfusion tracer in myocardial PET. J Nucl Med 2001, 42(8):1174-1182. PDF