fit_sinf 0.8.9 © 2005-2013 by Turku PET Centre
Fit the time-activity curve (TAC) of PET tracer in plasma or blood
to a four-to-ten parameter function (1). This function may be applied
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)))]
Command-line arguments:
1) TAC filename
2) Filename for fitted function parameters (optional)
TAC data must be in DFT format (2). For a good fit, (radioactivity)
concentrations should be corrected for physical decay and
circulating metabolites.
Function parameters will be written in the parameter file (3).
Command-line options:
-fast or -safe
Speed up the fitting but increase the chance of failure, or
increase the reliability at the cost of computing time.
-fit=<Filename>
Fitted TACs are written in DFT 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
-tau1=<Dispersion time constant (s)>
-tau2=<2nd dispersion time constant (s)>
Dispersion is added to function, also to saved curve and plot;
curve without dispersion can be calculated from function parameters.
-wf
Weight by sampling interval.
-min=<SS|ABS>
Sum-of-squares (SS) is minimized by default, but optionally
sum of absolute deviations can be selected.
-h or --help
Print this message and exit
--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
Options for constraining the fit:
-lim=<filename>
Specify the constraints for model parameters;
This file with default values can be created by giving this
option as the only command-line argument to this program.
-Ti=<infusion time>
Duration of tracer infusion; 0, if short bolus.
-Ta=<appearance time>
Time when tracer concentration starts ascending.
-n=<1|2|3|4|5|A>
The nr of summed functions; A=determined by AIC (default).
2 or 3 is usually recommended (much faster).
References:
1. Oakes ND et al. J Lipid Res. 1999;40:1155-1169.
2.
http://www.turkupetcentre.net/analysis/doc/format_dft.html
3.
http://www.turkupetcentre.net/analysis/doc/format_fit.html
See also:
fit2dat,
fit_feng,
fit_winp,
fit_exp,
fit_ratf,
extrapol
Keywords: input, modelling, simulation
This program comes with ABSOLUTELY NO WARRANTY. This is free software, and
you are welcome to redistribute it under GNU General Public License.