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 :
  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]
 -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.
     The nr of summed functions; A=determined automatically (default).
     Changing the default may lead to a bad fit.
     Weight by sampling interval.
     Error is returned if MRL check is not passed.
     Fitted parameters are also written in result file format.
     Fitted and measured TACs are plotted in specified SVG file.
     Initial part of fitted and measured TACs are plotted in SVG file
     Lower part of fitted and measured TACs are plotted in SVG file
     Fitted TACs are written in TAC format.
     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.
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