fitdelay 2.0.3 © 1999-2009 by Turku PET Centre
For estimation and correction of the time delay (difference in appearance
times of radioactivity) between blood or plasma and PET time-activity
curves (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.
Command-line arguments:
1) Blood or plasma TAC filename
2) Tissue TAC filename
3) Fit time (s)
4-5) Upto three additional blood or plasma files (optional)
Options:
-o=<Filename>
-o2=<Filename>
-o3=<Filename>
-o4=<Filename>
Filename(s) for the time delay corrected TAC(s) can be speficied with
these options; by default the file names for result files are formed as
is told below.
-timeunit=<min|sec>
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.
-format=<none|dft>
Specify the output data format; none means that no title lines are saved.
-fit=<Filename>
Fitted best TACs are written is specified file.
-model=<1|2>
Select whether 1- or 2-tissue (default) compartment model is applied.
-L[og]
Time delay and other log information is written as comments in
the corrected TAC file.
-h or --help
Print this message and exit
--version or --build
Print software build information and exit
--verbose
Program prints more information about what it is doing
--silent
Program works silently, printing only warnings and error messages.
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 ut345dy1.img.cr 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
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).
Estimated tracer appearance times in blood/plasma and tissue curves, and
their differences (time delays and median time delay) are written in stdout.
Delay corrected blood/plasma file is written with name *.delay.* ;
the same correction can be applied to 1-3 additional files, for
example plasma metabolite TACs.
References:
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.
5.
http://www.turkupetcentre.net/analysis/doc/format_dft.html
See also:
dfttime,
ecathead,
dfthead,
tocr,
dftrmbkg,
dftunit,
fit_h2o
Keywords: dft, modelling, input, blood, time delay
This program comes with ABSOLUTELY NO WARRANTY. This is free software, and
you are welcome to redistribute it under GNU General Public License.