fit_trtm - tpcclib 0.8.0 © 2023 by Turku PET Centre
NLLSQ estimation of R1 (=K1/K1'), k2', and k3 applying the 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
metabolism of tracer is irreversible (k4=0) during the PET scanning, and that
in (positive) reference tissue k3'>>k2', and thus the uptake in it is limited
only by transport into tissue (3,4).
Usage: fit_trtm [Options] ttacfile reference endtime resultfile
TTAC file can be in DFT or PMOD format. Sample times must be in minutes.
If TTAC file contains weights, those are used in the NLLSQ fitting.
Reference region TAC can be given separate TAC file or as the name or number
of the reference region in TTAC file.
Constrain k2' to specified <value>, or to mean or median of regional
k2' values excluding reference region(s)
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.
Standard deviations are calculated and saved in results (y), or
not calculated (n).
95% Confidence limits are calculated and saved in results (y), or
not calculated (n).
All weights are set to 1.0 (no weighting); by default, weights in
TTAC file are used, if available.
Weight by sampling interval.
Fitted regional TACs are written in file.
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.
Values of R1, k2, and k3 are written in the specified result file.
Fitted curves are written in DFT format, if file name is given.
Example 1: file a789.tac contains regions-of-interest and positive reference
region, with name 'putam'. The whole time range is used in the fit.
Fitted TACs are plotted in SVG format in file a789trtm.svg.
fit_trtm -svg=a789trtm.svg a789.tac putam 999 a789.res
Example 2: Reference region TAC is in a separate file, a789ref.tac.
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.tac a789ref.tac 60 a789.res
Example 3a: Create a file containing default parameter limits:
Example 3b: Apply user-defined parameter constraints specified in trtm.lim:
fit_trtm -lim=trtm.lim a789.tac 'putam mean' 999 a789.tac
1. Oikonen V. Model equations for reference tissue compartmental models.
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.
See also: fitk3, tacweigh, fit_rrtm, lhtrtm, sim_rtcm, rescoll
Keywords: TAC, modelling, irreversible uptake, RTCM, reference input