Calculates the net influx (uptake) rate constant Ki (ml/(min*ml)) as slope of the Patlak plot (1,2,3) from regional PET time-activity curves (TTACs). Usage: patlak [Options] ttac_file input start_time end_time result_file Input can be either a TAC file containing arterial plasma PTAC or reference region TAC, or name or number of reference region in the TTAC file. Start and end times of the line fit to the plot must be given in minutes. Options for calculation of metabolic rate: -Ca=<value> Concentration of native substrate in arterial plasma (mM), for example plasma glucose in [18F]FDG studies. With this option the metabolic rate (umol/(min*100 g)) is calculated. -LC=<value> Lumped Constant in MR calculation; default is 1.0. -density=<value> Tissue density in MR calculation; default is 1.0 g/ml. General options: -ic=<y axis intercept> Force y axis intercept to specified value; for FUR or Ri calculation use regfur. -sd=<y|n> Standard deviations are saved (y, default) or not saved (n) in results. -mid=<Y|n> Frame middle times are used (y), or not used (n, default), even if frame start and end times are available. For compatibility with old software. -svg=<Filename> Plots are written in specified file in Scalable Vector Graphics (SVG) 1.1 format; specification in http://www.w3.org/TR/SVG/ -plotdata=<Filename> Data for plots is written in specified file in XHTML table format for easy importing in Excel or OpenOffice spreadsheet, where the data can be viewed; if filename extension is .dft, data is written in DFT format -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. Options for selecting the least-squares line fit method: -C Traditional regression model (default) -M Median of two-point slopes and intercepts (Cornish-Bowden) -P Perpendicular regression model (4) -R Iterative method (York 1966, Lybanon 1984, Reed 1992) In the present software version, the weights are not used in the fit. Example 1: tissue curves are in ut1234.tac and plasma curve in ut1234ap.dat; fitted data range is from 10 to 60 min; standard deviations are not needed; plot is saved in file ut2345patlak.svg patlak -sd=n -svg=ut1234patlak.svg ut1234.tac ut1234ap.dat 10 60 ut1234.res Example 2: tissue curves in ut1234.tac, including reference region 'cer' patlak ut1234.tac cer 10 60 ut1234.res References: 1. Gjedde A. Calculation of cerebral glucose phosphorylation from brain uptake of glucose analogs in vivo: a re-examination. Brain Res. 1982; 257:237-274. 2. Patlak CS, Blasberg RG, Fenstermacher JD. Graphical evaluation of blood-to-brain transfer constants from multiple-time uptake data. J Cereb Blood Flow Metab 1983;3:1-7. 3. Patlak CS, Blasberg RG. Graphical evaluation of blood-to-brain transfer constants from multiple-time uptake data. Generalizations. J Cereb Blood Flow Metab 1985;5:584-590. 4. Varga J & Szabo Z. Modified regression model for the Logan plot. J Cereb Blood Flow Metab 2002; 22:240-244. See also: imgki, fitk3, fitkloss, lhsolki, regfur, logan, rescoll Keywords: TAC, MTGA, Patlak plot, modelling, Ki