Simulation of PET tissue time-radioactivity concentration curves (TACs) from arterial plasma (Ca) and blood (Cb) TACs, based on three-tissue compartmental model, where the compartments are in series (default): ____ K1 ____ k3 ____ k5 ____ | Ca | ----> | C1 | ----> | C2 | ----> | C3 | |____| <---- |____| <---- |____| <---- |____| k2 k4 k6 dC1(t)/dt = K1*Ca(T) - (k2+k3)*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*C3(T) Ct(T) = C1(T) + C2(T) + C3(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, three-tissue compartmental model, where the 2nd and 3rd tissue compartments are parallel, often used to represent specific and non-specific binding: ____ K1 ____ k3 ____ | Ca | ----> | C1 | ----> | C2 | |____| <---- |____| <---- |____| k2 k4 | ^ k5 | | k6 v | ____ | C3 | |____| dC1(t)/dt = K1*Ca(T) - (k2+k3+k5)*C1(T) + k4*C2(T) + k6*C3(T) dC2(t)/dt = k3*C1(T) - k4*C2(T) dC3(t)/dt = k5*C1(T) - k6*C3(T) Ct(T) = C1(T) + C2(T) + C3(T) Cvb(T) = Cab(T) - dCt(t)/dt / f Cpet(T)= Vb*fA*Cab(T) + Vb*(1-fA)*Cvb(T) + (1-Vb)*Ct(T) Usage: sim_3tcm [options] parfile [plasmafile bloodfile simfile] Options: -paral[lel] Model with parallel compartments C2 and C3 is applied, overriding possible model settings in parameter file. -ser[ies] Model with compartments C1, C2, and C3 in series is applied, overriding possible model settings in parameter file. -vvm=<1|2> Vascular volume is modelled as (1, default) Cpet(T)= Vb*fA*Cab(T) + Vb*(1-fA)*Cvb(T) + (1-Vb)*Ct(T) or as (2) Cpet(T)= Vb*fA*Cab(T) + Vb*(1-fA)*Cvb(T) + Ct(T). -sub | -nosub TACs of sub-compartments (C1, C2 and C3) are written (-sub) or not written (-nosub, default) into the simfile. -h, --help Display usage information on standard output and exit. -v, --version Display version and compile information on standard output and exit. -d[n], --debug[=n], --verbose[=n] Set the level (n) of debugging messages and listings. -q, --quiet Suppress displaying normal results on standard output. -s, --silent Suppress displaying anything except errors. To create a template parameter file, do not enter names for input and simulated TACs. Obligatory parameters are: K1, k2 (or K1/k2), k3, k4 (or k3/k4), k5, k6 (or k5/k6), and Vb. Additionally, values for perfusion (f), arterial fraction of Vb (fA), and delay time (dT) can be set; otherwise it is assumed that f>>K1, Cvb=Cab, fA=1, and dT=0. If parameter file does not contain units, then per min and per mL units are assumed, except sec for dT. For accurate results, plasma TAC should have very short sampling intervals. To reduce the model, k5 or k3 can be set to 0. When blood file is not used (Vb=0), 'none' can be entered in its place. See also: simdisp, p2t_di, sim_rtcm, tacadd, simframe, tacformat, dft2img Keywords: TAC, simulation, modelling, compartmental model