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 --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 and 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.

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Last updated 2008-07-21