fit_trtm 2.6.3 © 1999-2012 by Turku PET Centre
Estimates R1 (=K1/K1'), k2' and k3 (assumption: k4=0) using transport-
limited reference tissue compartment model, TRTM (1). This model
is based on the reference tissue compartment model (2), but here it is
assumed that in reference tissue k3'>>k2', and thus the uptake in it is
limited only by transport into tissue (3,4).
______ K1' __________________
| | --> | k3' |
| | <-- | Crf ------> Crb |
| | k2'|__________________|
| Cp | _________ ________
| | K1 | k3| |
| | --> | Cf ------> Cb |
| | <-- | | |
|______| k2 |_________|________|
Cr(t) = Crf(t) + Crb(t) ; Ct(t) = Cf(t) + Cb(t)
dCt(t) = R1*dCr(t) + (R1*k3)*Cr(t) - (R1*k2'+k3)*Ct(t)
Command-line parameters:
1) Tissue TAC file (5)
2) Name or number of reference region in tissue file, or name of TAC file
containing reference tissue TAC
3) Fit time (in minutes from injection)
4) Result file (existing file is overwritten) (6)
Options:
-rk2=<<value>|mean|median>
Constrain k2' to specified <value>, or to mean or median of regional
k2' values excluding reference region(s)
-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
-SD[=<y|N>]
Standard deviations are calculated and saved in results (y), or
not calculated (n)
-CL[=<y|N>]
95% Confidence limits are calculated and saved in results (y), or
not calculated (n)
-fit=<Filename>
Fitted regional TACs are written in DFT format (5).
-svg=<Filename>
Fitted and measured TACs are plotted in specified SVG file (7).
-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
If datafile contains weights, those are used in the fitting.
Example 1: file a789.dft contains regions-of-interest and reference region,
with name 'putam'. The whole time range is used in the fit.
Fitted TACs are plotted in SVG format (7) in file a789trtm.svg.
fit_trtm -svg=a789trtm.svg a789.dft putam 999 a789.res
Example 2: Reference region TAC is in a separate file, a789ref.dft.
Standard deviations and confidence limits are also estimated.
TAC data from injection to 60 min is used in the fitting.
fit_trtm -SD=y -CL=y a789.dft a789ref.dft 60 a789.res
Example 3a: Create a file containing default parameter limits:
fit_trtm -lim=trtm.lim
Example 3b: Apply user-defined parameter constraints specified in trtm.lim:
fit_trtm -lim=trtm.lim a789.dft putam 999 a789.res
References:
1. Oikonen V. Model equations for reference tissue compartmental models.
http://www.turkupetcentre.net/reports/tpcmod0002.pdf
2. Cunningham VJ, Hume SP, Price GR, Ahier RG, Cremer JE, Jones AKP.
Compartmental analysis of diprenorphine binding to opiate receptors
in the rat in vivo and its comparison with equilibrium data in vitro.
J Cereb Blood Flow Metab 1991;11:1-9.
3. Herholz K, Lercher M, Wienhard K, Bauer B, Lenz O, Heiss W-D.
PET measurement of cerebral acetylcholine esterase activity without
blood sampling. Eur J Nucl Med 2001;28:472-477.
4. Nagatsuka S, Fukushi K, Shinotoh H, Namba H, Iyo M, Tanaka N, Aotsuka A,
Ota T, Tanada S, Irie T. Kinetic analysis of [11C]MP4A using a high-
radioactivity brain region that represents an integrated input function
for measurement of cerebral acetylcholinesterase activity without
arterial blood sampling. J Cereb Blood Flow Metab 2001; 21: 1354-1366.
5. File format specification: DFT.
http://www.turkupetcentre.net/formats/format_dft_1_0_0.pdf
6. File format specification: Result file.
http://www.turkupetcentre.net/formats/format_res_1_0_0.pdf
7. Scalable Vector Graphics (SVG) 1.1 Specification.
http://www.w3.org/TR/SVG/
See also:
dftweigh,
fitk3,
fitshape,
lhtrtm,
r2t_rtcm,
rescoll
Keywords: DFT, modelling, irreversible uptake, reference tissue
This program comes with ABSOLUTELY NO WARRANTY. This is free software, and
you are welcome to redistribute it under GNU General Public License.
