hm4mpa 1.4.0 © 2000-2008 by Turku PET Centre
Estimates the brain ACh esterase (AChE) activity (k3) from regional
time-activity concentration curves (TACs) using a reference tissue input
model dedicated to [C-11]MP4A brain PET studies (1).
The model assumptions are:
1) hydrolysis is irreversible (k4=0)
2) In reference tissue (striatal or cerebellum region) hydrolysis is very
rapid (k3>>k2)
3) Plasma activity can be approximated by mono-exponential function
4) Hydrolysis is very rapid in plasma (compared to tissue).
Note that because of these assumptions the method cannot be used to analyze
AChE inhibitor studies.
In this method, first a ratio curve (tissue relative to reference tissue)
is calculated. Then a function R(t)=A*exp(-k*t)+B is fitted to the ratio
curve. The k3 is solved from the fitted parameters as k3=(B*k)/(A+B).
Command-line parameters:
1) Tissue TAC file
2) Name or number of reference region in tissue file, or name of file
containing reference tissue TAC
3) Fit time (in minutes from injection)
4) Result file (existing file is overwritten)
Options:
-h or --help
Print this message and exit
-svg=<Filename>
Fitted and calculated ratio curves are plotted in specified file in
Scalable Vector Graphics (SVG) 1.1 format;
specification in
http://www.w3.org/TR/SVG/
--version or --build
Print software build information and exit
--silent
Program works silently, printing only error and warning messages
--verbose
Program prints lots of information about what it is doing.
Format of the TAC data and result files are specified in
http://www.turkupetcentre.net/analysis/doc/format_dft.html and
http://www.turkupetcentre.net/analysis/doc/format_res.html
If tissue TAC file contains weights, those are used in the fitting;
weighting the data is recommended.
Example 1: File b4457.dft contains the TACs of regions-of-interest and
reference region with name PUTAM. The whole time range is used in the fit.
Fits are plotted in file b4457hm.svg.
hm4mpa -svg=b4457hm.svg b4457.dft putam 999 b4457.res
References:
1. 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(4):472-477.
See also:
dftweigh,
dftratio,
fit_trtm,
r2t_rtcm,
rescoll
Keywords: DFT, modelling, reference input, enzyme activity, AChE
This program comes with ABSOLUTELY NO WARRANTY. This is free software, and
you are welcome to redistribute it under GNU General Public License.
