fitk4 - tpcclib 0.7.3 © 2019 by Turku PET Centre

Non-linear fitting of two-tissue compartment model to plasma input, blood,
and tissue time-activity curves (PTAC, BTAC, and TTAC) to estimate
parameters K1, K1/k2, k3, k3/k4, and Vb.
Optionally, K1/k2 can be constrained to the value estimated in reference
region; either 1- (default) or 2-tissue compartmental model can be fitted to
reference region data.
 
    ______       ___________________           
   |      |  K1 |        k3         |          
   |      | --> |      ------->     |          
   |  Ca  | <-- |   C1 <------- C2  |          
   |      |  k2 |        k4         |          
   |______|     |___________________|          
 
Sample times must be in minutes.
 
Usage: fitk4 [Options] ptacfile btacfile ttacfile endtime resultfile
 
Options:
 -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.
     Without filename the default values are printed on screen.
 -SD[=<y|N>]
     Standard deviations are estimated and saved in results (y),
     or not calculated (N, default).
     Program runs a lot faster if SD and CL are not calculated.
 -CL[=<y|N>]
     95% Confidence limits are estimated and saved in results (y), or
     not calculated (N, default).
 -Vb=<Vb(%)>
     Enter a fixed Vb; fitted by default.
 -fk1k2=<<value> || <result filename>>
     K1/k2 is constrained to the given value in all regions; if result
     filename is entered, then K1/k2 is constrained to the median of
     regional K1/k2 values in the result file.
 -r=<Reference region id or filename>
     Optional reference region is used to constrain K1/k2 in other regions;
     with option -rmod=3 also k3 and k4 are fitted to reference region data,
     thus any large brain region (for example cortex) could be used here.
 -rmod=<2|3>
     Specify the model (2- or 3-compartments) that is fitted to reference
     region data; by default 2-CM (1-tissue compartment model).
 -BPnd[=<reference region id>]
     BPnd is calculated as BPnd=VtROI/VtREF-1; reference region name
     is not needed if the same is specified with option -r.
 -fit=<Filename>
     Fitted regional TACs are written in DFT format.
 -svg=<Filename>
     Fitted and measured TACs are plotted in specified SVG file.
 -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.
 
Example 1: estimate K1, K1/k2, k3, k3/k4 and Vb, and report also BPnd using
region 'cereb' as reference region
     fitk4 -BPnd=cereb ua919ap.bld ua919ab.bld ua919.tac 60 ua919.res
 
Example 2: estimate K1, k3 and k3/k4; Vb is constrained to 1.5% and K1/k2 is
constrained to K1/k2 estimated from region 'occip' with 1-tissue compartment
model
     fitk4 -Vb=1.5 -r=occip -rmod=2 ua919ap.bld ua919ab.bld ua919.tac 60 ua919.res
 
Example 3: constrain K1/k2 to the regional median; Vb is set to 4%;
     fitk4 -Vb=4 ua919ap.kbq ua919ab.kbq ua919.dft 60 tmp.res
     fitk4 -Vb=4 -fk1k2=tmp.res ua919ap.kbq ua919ab.kbq ua919.dft 60 ua919.res
 
See also: logan, fitk2, fitk3, fitk5, p2t_v3c, tacweigh, dftcbv, rescoll
 
Keywords: TAC, modelling, binding potential, reversible uptake, 2TCM