Calculate the distribution volume (Vt) or distribution volume ratio (DVR) using multiple-time graphical analysis (MTGA) for reversible PET ligands (Logan plot) (1,2,3) from regional PET time-activity curves (TTACs). Usage: logan [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: -k2=<reference region k2> With reference region input, the population average of reference region k2 (or k2/(1+k5/k6) in 3-compartment model) is set. -BPnd With reference input, BPnd (=DVR-1) is reported instead of DVR -BPnd=<reference region name> With plasma input, BPnd can be calculated as DVroi/DVref-1 -DVR=<reference region name> With plasma input, DVR can be calculated as DVroi/DVref -BPp=<reference region name> With plasma input, BPp can be calculated as DVroi-DVref -sd=<y|n> Standard deviations are saved (y, default) or not saved (n) in results. -mid[=<y|n>] Mid frame 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/ -bw Black-and-white plot. -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 file name 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 -M Median of two-point slopes and intercepts (Cornish-Bowden) -P Perpendicular regression model (4) -R Iterative method (York 1966, Lybanon 1984, Reed 1992); default If tissue file contains weights, the iterative method (-R) is weighted. With other fitting methods the weights are not used. With options -C and -R program can automatically find the linear plot range, if fit start time is set to zero. Example 1: tissue curves are in ut2345.tac and plasma curve in ut2345ap.dat; fitted data range is from 10 to 60 min; standard deviations are not needed, plot is saved in file ut2345logan.svg logan -sd=n -svg=ut2345logan.svg ut2345.tac ut2345ap.dat 10 60 ut2345.res Example 2: tissue curves in ut1234.tac, including reference region 'cer'; reference tissue k2 is assumed to equal 0.163 logan -k2=0.163 ut2345.tac cer 20 60 ut2345.res References: 1. Logan J, Fowler JS, Volkow ND, Wolf AP, Dewey SL, Schlyer DJ, MacGregor RR, Hitzemann R, Bendriem B, Gatley SJ, Christman DR. Graphical analysis of reversible radioligand binding from time-activity measurements applied to [N-11C-methyl]-(-)-cocaine PET studies in human subjects. J Cereb Blood Flow Metab 1990; 10: 740-747. 2. Logan J, Fowler JS, Volkow ND, Wang GJ, Ding YS, Alexoff DL. Distribution volume ratios without blood sampling from graphical analysis of PET data. J Cereb Blood Flow Metab. 1996; 16: 834-840. 3. Logan J. Graphical analysis of PET data applied to reversible and irreversible tracers. Nucl Med Biol 2000; 27:661-670. 4. Varga J & Szabo Z. Modified regression model for the Logan plot. J Cereb Blood Flow Metab 2002; 22:240-244. See also: imgdv, fitk2, fitk4, patlak, rescoll Keywords: TAC, MTGA, Logan plot, modelling, distribution volume, DVR