fitk4 - tpcclib 0.7.5 © 2020 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
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.
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.
95% Confidence limits are estimated and saved in results (y), or
not calculated (N, default).
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.
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.
Fitted regional TACs are written in DFT format.
Fitted and measured TACs are plotted in specified SVG file.
Display usage information on standard output and exit.
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.
Suppress displaying normal results on standard output.
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
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