p2t_di 0.1.1 © 2013 by Turku PET Centre
Simulation of PET tissue time-radioactivity concentration curve (TAC) using
dual-input four-tissue compartmental model. Input consists of parent tracer
and metabolite concentration curves in arterial plasma (Cap and Cam) and
total radioactivity concentration in arterial blood (Cb).
Tissue compartments for parent tracer are in series [1] (by default):
_____ K1 ____ k3 ____ k5 ____ k7
| Cap | ----> | C1 | ----> | C2 | ----> | C3 | ---->
|_____| <---- |____| <---- |____| <---- |____|
k2 | k4 k6
km|
v
_____ K1m ____
| Cam | ----> | C4 |
|_____| <---- |____|
k2m
dC1(t)/dt = K1*Cap(T) - (k2+k3+km)*C1(T) + k4*C2(T)
dC2(t)/dt = k3*C1(T) - (k4+k5)*C2(T) + k6*C3(T)
dC3(t)/dt = k5*C2(T) - (k6+k7)*C3(T)
dC4(t)/dt = K1m*Cam(T) + km*C1(T) - k2m*C4(T)
Ct(T) = C1(T) + C2(T) + C3(T) + C4(T)
Cvb(T) = Cab(T) - dCt(t)/dt / f
Cpet(T)= Vb*fA*Cab(T) + Vb*(1-fA)*Cvb(T) + (1-Vb)*Ct(T)
, or, optionally, the 2nd and 3rd tissue compartments are parallel [2],
often used to represent specific and non-specific binding:
____
| C3 | k7
|____| ---->
^ |
k5 | | k6
| v
_____ K1 ____ k3 ____
| Cap | ----> | C1 | ----> | C2 |
|_____| <---- |____| <---- |____|
k2 | k4
km|
v
_____ K1m ____
| Cam | ----> | C4 |
|_____| <---- |____|
k2m
dC1(t)/dt = K1*Ca(T) - (k2+k3+k5+km)*C1(T) + k4*C2(T) + k6*C3(T)
dC2(t)/dt = k3*C1(T) - k4*C2(T)
dC3(t)/dt = k5*C2(T) - (k6+k7)*C3(T)
dC4(t)/dt = K1m*Cam(T) + km*C1(T) - k2m*C4(T)
Ct(T) = C1(T) + C2(T) + C3(T) + C4(T)
Cvb(T) = Cab(T) - dCt(t)/dt / f
Cpet(T)= Vb*fA*Cab(T) + Vb*(1-fA)*Cvb(T) + (1-Vb)*Ct(T)
Command-line arguments:
1) Plasma parent TAC filename
2) Plasma metabolite TAC filename
3) Blood TAC filename
4-13) Rate constants K1, k2, k3, k4, k5, k6, k7, km, K1m, and k2m
14) Vascular volume fraction Vb (%)
15) Filename for simulated TACs
Options:
-paral[lel]
Model with parallel compartments C2 and C3 is applied.
-ser[ies]
Model with compartments C1, C2, and C3 in series is applied (default).
-f=<Perfusion (ml/(min*ml) or ml/(sec*ml))>
Difference between concentrations in venous and arterial blood can
be simulated if tissue perfusion (f>K1) is specified with this option
and arterial fraction of vascular volume is set with option -fA;
by default it is assumed that venous and arterial activities are
the same (f>>K1).
-fA=<Arterial fraction of vascular volume (%)>
Difference between concentrations in venous and arterial blood can
be simulated if arterial fraction of vascular volume is specified with
this option and tissue perfusion is set with option -f;
by default it is assumed that Vb consists of only arterial blood.
-sub | -nosub
TACs of sub-compartments (C1, C2 and C3) are written (-sub)
or not written (-nosub, default) into the output file.
-h or --help
Print this message and exit.
-v, --version or --build
Print software build information and exit.
--silent
Program works silently, printing only error and warning messages.
--verbose
Program prints more information about what it is doing.
If the times in plasma file are in seconds, the units of rate constants
(k's) and blood flow (f) must also be specified as 1/sec.
For accurate results, plasma TAC should have very short sampling intervals.
To reduce the model, k7, k5, and k3 can be set to 0.
Simulated TACs are written in ASCII format with columns:
1) Sample time
2) Total tissue activity concentration (Cpet)
3) Activity concentration in 1st tissue compartment, (1-Vb)*C1
4) Activity concentration in 2nd tissue compartment, (1-Vb)*C2
5) Activity concentration in 3rd tissue compartment, (1-Vb)*C3
6) Activity concentration in 4th tissue compartment, (1-Vb)*C4
7) Arterial concentration to tissue activity, Vb*fA*Cab (optional)
8) Venous contribution to tissue activity, Vb*(1-fA)*Cvb (optional)
References:
1. TPCMOD0001 Appendix B.
2. TPCMOD0001 Appendix C.
See also:
p2t_v3c,
dftadd,
dftren,
fr4sim,
dft2csv,
dft2img
Keywords: DFT, simulation, modelling, compartmental model, dual-input
This program comes with ABSOLUTELY NO WARRANTY. This is free software, and
you are welcome to redistribute it under GNU General Public License.