imgki - tpcclib 0.7.9 © 2022 by Turku PET Centre

Calculates the net influx (uptake) rate constant (Ki) from dynamic PET image
in ECAT, NIfTI, or Analyze format, applying the multiple time graphical
analysis (MTGA) approach for irreversible tracer uptake (Patlak plot).
Simple non-iterative perpendicular line fitting algorithm (4) is applied.
 
Usage: imgki [Options] input image starttime resultimage
 
Input can be either a TAC file containing arterial plasma PTAC or reference
region TTAC. Data must be in the same concentration units as the data in
image, and times in min; however, if units are specified inside the input
and image file, the program can automatically convert units.
Start time of the linear fit must be given in minutes; set to zero to
let the program automatically determine the start time (not recommended).
 
Options:
 -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.
 -thr=<threshold%>
     Pixels with AUC less than (threshold/100 x input AUC) are set to zero;
     default is 0%.
 -noneg
     Pixels with negative Ki are set to zero.
 -max=<Max value>
     Upper limit for Ki values.
 -filter
     Remove parametric pixel values that are over 4x higher than
     their closest neighbours.
 -end=<Fit end time (min)>
     By default line is fitted to the end of data. Use this option to enter
     the fit end time.
 -v=<filename>
     Y axis intercepts are written as an image in specified file.
 -n=<filename>
     Numbers of selected plot data points are written as an image.
 -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.
 
Example 1. Calculation of Ki image, starting linear fit from 20 minutes:
     imgki ua2918ap.kbq ua2918dy1.v 20 ua2918ki.v
 
Example 2. Calculation of glucose uptake image, when tissue density is 1.02,
           plasma glucose concentration is 5.2 mM, lumped constant is 1.0,
           starting linear fit from 10 minutes after radiotracer injection:
     imgki -density=1.02 -Ca=5.2 -LC=1.0 s8642ap.kbq s8642dy1.v 10 s8642ki.v
 
The unit of pixel values in the parametric (Ki) image is
(mL plasma)/(min*(mL tissue)) by default, and umol/(min*100 g) in metabolic
rate image.
 
To calculate Ki images from [18F]FDOPA studies with plasma input:
subtract reference region TAC from dynamic image before using this program.
 
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: imgfur, imgbound, imgunit, imglhki, img2tif, patlak
 
Keywords: image, MTGA, Patlak plot, modelling, Ki, metabolic rate