fit_sinf - tpcclib 0.7.3 © 2019 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