fitk4 - tpcclib 0.8.0 © 2023 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, taccbv, rescoll
Keywords: TAC, modelling, binding potential, reversible uptake, 2TCM