fit_sinf - tpcclib 0.8.0 © 2023 by Turku PET Centre
Non-linear fitting of the exponential based function (Wagner, 1976)
to the PET plasma or blood time-activity curve (TAC). This function can
be used when PET tracer is introduced into venous blood as a short infusion.
Function: f(t)=
if t<=Ta :
0
if t>Ta and t<Ta+Ti :
(1/Ti)*Sum[i=1..n, (Ai/Li)*(1-exp(-Li*(t-Ta)))]
if t>=Ta+Ti :
(1/Ti)*Sum[i=1..n, (Ai/Li)*(exp(-Li*(t-Ta-Ti)) - exp(-Li*(t-Ta)))]
Usage: fit_sinf [Options] tacfile [parfile]
Options:
-Ti=<infusion time>
Duration of tracer infusion; 0, if short bolus.
-Ta=<appearance time>
Time when tracer concentration starts ascending.
-tau1=<Dispersion time constant (s)>
-tau2=<2nd dispersion time constant (s)>
Dispersion is added to function, also to saved curve and plot.
-n=<1|2|3|4|5|A>
The nr of summed functions; A=determined automatically (default).
Changing the default may lead to a bad fit.
-wf
Weight by sampling interval.
-MRL
Error is returned if MRL check is not passed.
-res=<Filename>
Fitted parameters are also written in result file format.
-svg=<Filename>
Fitted and measured TACs are plotted in specified SVG file.
-svg1=<Filename>
Initial part of fitted and measured TACs are plotted in SVG file
-svg2=<Filename>
Lower part of fitted and measured TACs are plotted in SVG file
-fit=<Filename>
Fitted TACs are written in TAC format.
-dcfit=<Filename>
Fitted dispersion corrected TAC is written in given file;
same output as with -fit when tau1 and tau2 are not set.
-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.
TAC file must contain two columns, sample times (x) and concentrations (y);
any additional columns are ignored. For a good fit, TAC should be corrected
for physical decay and circulating metabolites.
Function parameters (Ta, Ti, A1, L1, ...) will be written in the parfile.
References:
1. Wagner JG. J Pharmacokin Biopharm. 1976;4:443-467.
2. Kudomi N et al. Eur J Nucl Med Mol Imaging 2008;35:1899-1911.
See also: fit2dat, fit_feng, fit_exp, fit_ratf, extrapol, disp4dft
Keywords: curve fitting, input, modelling, simulation, dispersion