Card. Rb-82 (1 Compartment)

The model has the standard 1-compartment form

with the differential equation

The equation assumes that the activity in the left ventricle C_lv(t) is used as the input curve.

Rb is known to have a flow-dependent extraction fraction, so that K₁ , which is the product of flow F times extraction fraction E, is described by the expression

The values of the correction factors reported by Lortie et al. [44] are

A = 0.77
B = 0.63 [ml/min/g]

The model implements a geometric double spillover correction for activity from the left and right ventricle in the form

where
V_lv = spill-over fraction of the blood activity in the left ventricle C_lv(t),
V_rv = spill-over fraction of the blood activity in the right ventricle C_rv(t) .

Implementation Notes:

• The right ventricle curve is only used for spillover correction of septal TACs. It must be loaded as the Total blood curve.
• The left ventricle curve serves two purposes: (1) as the input curve, (2) it is used for spillover correction of all myocardial TACs. It must be loaded as the Input curve.
• In practice, the expression for K₁ is inserted into the differential equation, so that F becomes a fit parameter, and K₁ is a derived parameter.
• To allow the user to change the form of the extraction function the scale factor A and the exponent B an be entered as input parameters.
• 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 of the regional TAC. 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. The reason for this automatism is usage of the model in the PCARDP tool.
• To set V_rv = 0 in all regional models proceed as follows: in one region, set V_rv =0 and disable the fit checkbox; fit the region; configure the button below Copy to all regions to Model and Par. and activate it.

This model is also usable in the cardiac modeling tool PCARDP.