Fits an empirical function to plasma parent (unchanged) tracer fraction curve (1), where the fractions are between 0 and 1. Usage: fit_ppf [Options] fractionfile [fitfile] Options: -model=<PF | HILL | MPF | MHILL> Select the function (see descriptions below); default is HILL. Use MPF or MHILL to fit functions to 2-3 metabolite fraction curves instead of parent fraction curve. -min=<OLS|LAD|ODR> Sum-of-squares (ordinal least squares, OLS) is minimized by default, but optionally, sum of absolute deviations (LAD), or sum-of-squares of Akaho distances (orthogonal distances, ODR) can be selected. ODR can be used only with PF and HILL. -delaymin=<value> Set the lower limit for delay parameter. -mdelay=<separated | joint> Delay parameter for each metabolite is fitted separately, or all metabolites are assumed to share common delay time (default). -fix0 Parent fraction at time zero is fixed to zero sample, if available. -a=<value>, -b=<value>, -c=<value>, ... Specified parameter is fixed to given (population mean) value. Option -fix0 overrides option -d=<value> when possible. -WC The last data column contains sample weights. -W1 All weights are set to 1.0 (no weighting) -WF Less frequent samples are given more weight. -WP=<weight>, -WM1=<weight>, -WM2=<weight>, -WM3=<weight> Put additional or less weight to parent and/or metabolite fractions. -ND Some fractions are known to exceed 1, not divided by 100. -MRL Error is returned if MRL check is not passed. -svg=<Filename> Fitted and measured TACs are plotted in specified SVG file. -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. Fraction datafile must contain at least two columns: sample times (min) and fractions of parent tracer. Fractions of 1-3 metabolites can be given in additional columns. Weights column can be given as specified in DFT format (2) or with option -wc. Program writes the fit start and end times, nr of points, WSS, and parameters of the fitted function to the FIT file (3). Available functions: PF - extended power function (1,4,5) f(x) = {D^(-1/C) + (A*(x-E))^B }^-C , when x>E, f(x) = D , when x<=E , where 0<A<=1, B>1.5, C>0, 0<D<=1, 0<=E. With option -d=1 this is essentially the same function as proposed in (4) or with options -b=2 -d=1 -e=0 the same as suggested in (5). HILL - Extended Hill type function (1,6) f(x) = D - {(D-A)(x-E)^B}/{C+(x-E)^B} , when x>E, f(x) = D , when x<=E , where 0<=A<=D, 1<=B, 0<C, 0<D<=1, 0<=E. With options -d=1 -e=0 this is the traditional Hill type function (6) f(x) = 1 - {(1-A)x^B}/(C+x^B) MPF - Extended power function is fitted to 1-3 metabolite fractions. MHILL - Extended Hill type function is fitted to 1-3 metabolite fractions. References: 1. Fitting the fractions of parent tracer in plasma. http://www.turkupetcentre.net/petanalysis/input_parent_fitting.html 2. http://www.turkupetcentre.net/petanalysis/format_tpc_dft.html 3. http://www.turkupetcentre.net/petanalysis/format_tpc_fit.html 4. Meyer PT, Bier D, Holschbach MH, Boy C, Olsson RA, Coenen HH, Zilles K, Bauer A. Quantification of cerebral A1 adenosine receptors in humans using [18F]CPFPX and PET. J Cereb Blood Flow Metab. 2004;24(3):323-333. 5. Watabe H, Channing MA, Der MG, Adams HR, Jagoda E, Herscovitch P, Eckelman WC, Carson RE. Kinetic analysis of the 5-HT2A ligand ([11C]MDL 100,907. J Cereb Blood Flow Metab 2000;20:899-909. 6. Wu S, Ogden RT, Mann JJ, Parsey RV. Optimal metabolite curve fitting for kinetic modeling of 11C-WAY-100635. J Nucl Med 2007;48:926-931. See also: fit2dat, metabcor, avgfract, fitedit, fit_fexp, fith2met, tac2svg Keywords: input, plasma, modelling, simulation, metabolite correction