fitdelay - tpcclib 0.8.0 © 2023 by Turku PET Centre

For estimation and correction of the delay-time (difference in appearance
times of radioactivity) between PET tissue and input (blood or plasma) TACs.
Program is based on the methods used by Meyer et al. (1) and
van den Hoff et al. (2):
The plasma/blood curve is shifted -60 - +60 sec, and a two-tissue
compartment model (with parameters K1, k2, k3, k4 and Vb) in multilinear
form (3) is fitted to the shifted TAC and each regional tissue TAC,
with the nonnegative least squares method (4).
For each region, the delay leading to the lowest sum-of-squares is selected;
the over-all delay value is calculated as a median of the regional delays.
Dispersion is not considered in this application.
Usage: fitdelay [options] inputfile tissuefile fittime [inputfile2 [inputfile3 [inputfile4]]]
     Filename for the time delay corrected TAC made from inputfile.
     Filename for the time delay corrected TAC made from inputfile2.
     Filename for the time delay corrected TAC made from inputfile3.
     Filename for the time delay corrected TAC made from inputfile4.
     If datafile(s) do not contain the unit of sample times, it is
     recommended to specify it with this option. By default, units in data
     files are trusted.
     Specify the output data format; none means that no title lines are saved.
     Filename for fitted best TACs; by default these are not saved.
     Select whether 1- or 2-tissue (default) compartment model is applied.
     Time delay and other log information is written as comments in
     the corrected TAC file, if format supports comments.
     Filename for saving NNLS matrix in CSV format for testing purposes.
     With this option the tissue file must contain one TAC only.
 -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.
As tissue data, the scanner countrate curve is recommended, unless scanned
volume contains heart or large artery or vein where tracer was injected;
It may be possible to use also regional TACs, if datafile contains frame
start and end times. If tissue data contains background, remove it first
with dftrmbkg. The units of sample times should be specified in datafiles;
file format is specified in (5).
Fittime must be given in seconds.
Estimated tracer appearance times in blood/plasma and tissue curves, and
their differences (time delays and median time delay) are written in stdout.
By default, delay corrected blood/plasma file is written with name *.delay.*
but this can be changed with option -o=<Filename>.
The same correction can be applied to 1-3 additional files, for
example plasma metabolite TACs.
Example 1.
Delay correction for C-11 or F-18 labeled tracer data, using
metabolite corrected plasma curve as input and count-rate data as tissue
and correcting also plasma metabolites and total blood for the delay-time:
   fitdelay ut345ap_pure.kbq 1800 ut345ap_met.kbq ut345ab.kbq
Example 2.
Delay correction for [O-15]water data, using regional tissue
curves as replacement for count-rate data:
   fitdelay ut111ab.kbq ut111dy1.dft 120
 1. Meyer. Simultaneous correction for tracer arrival delay and dispersion
    in CBF measurements by the H215O autoradiographic method and dynamic PET.
    J Nucl Med 1989; 30:1069-1078.
 2. van den Hoff et al. Accurate local blood flow measurements with
    dynamic PET: fast determination of input function delay and dispersion
    by multilinear minimization. J Nucl Med 1993; 34:1770-1777.
 3. Blomqvist G. On the construction of functional maps in positron
    emission tomography. J Cereb Blood Flow Metab 1984; 4:629-632.
 4. Lawson CL & Hanson RJ. Solving least squares problems.
    Prentice-Hall, 1974.
See also: tactime, imghead, tacmean, tocr, dftrmbkg, tacunit, fit_h2o
Keywords: TAC, modelling, input, blood, time delay