imgflowm - tpcclib 0.8.0 © 2023 by Turku PET Centre

Estimation of rate constants K1 (perfusion), k2 and Va from dynamic
radiowater PET image in ECAT 6.3, ECAT 7.x, NIfTI-1, or Analyze 7.5 file
format using. The two-compartment model equations
  dCt(t)/dt = K1*Ca(t) - k2*Ct(t)
  Croi(t) = Va*Ca(t) + Ct(t)
are linearized (1) into equation
  Croi(t) = Va*Ca(t) + (K1+Va*k2)*Integral[Ca(t)] - k2*Integral[Croi(t)]
from which the model parameters are solved using Lawson-Hanson non-negative
least squares (NNLS) method (2).
Arterial blood curve (BTAC) must be corrected for decay and time delay,
with sample times in seconds. Dynamic PET image must be corrected for decay.
Since time delay varies inside PET image, this program requires a mask image
which specifies to which pixels the model is applied. If output file(s) do
not exist, the output files are created with zero pixel values where mask
image has value 0. If output file(s) exist, the pre-existing pixel values
outside the mask are not changed.
Usage: imgflowm [Options] btacfile imgfile maskfile flowfile
 -end=<Fit end time (sec)>
     Use data from 0 to end time; by default, all of it.
     Parametric k2 image is saved; in some situations perfusion calculation
     from k2 can be more accurate than the default assumption of f=K1.
     Perfusion can be calculated from k2 using equation f=k2*pH2O, where
     pH2O is the physiological partition coefficient of water in tissue.
 -Va=<filename> | -Va=0
     Parametric Va image is saved, or set Va to 0 if image is pre-corrected
     for arterial blood volume; by default Va is fitted.
 -max=<Max value>
     Upper limit for blood flow (K1) values.
     Pixels with negative K1 estimates are set to zero.
 -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.
The units of pixel values in the blood flow (K1) image is
(mL blood)/((mL tissue) * min), in k2 image 1/min, and
in Va image (mL blood/mL tissue).
Example 1. Calculation of perfusion and arterial blood volume image,
           stopping fit at 180 s:
  imgflowm -Va=p234va.v -end=180 p234d1.bld p234.nii p234_mask1.nii p234flow.nii
Example 2. Dynamic image is pre-corrected for vascular activity,
           and full data length is used:
  imgflowm -Va=0 p345dc2.bld p345_vacorr.nii p345flow.nii
1. Blomqvist G. On the construction of functional maps in positron
   emission tomography. J Cereb Blood Flow Metab. 1984;4:629-632.
2. Lawson CL & Hanson RJ. Solving least squares problems.
   Prentice-Hall, 1974.
3. Ohta S, Meyer E, Thompson CJ, Gjedde A. Oxygen consumption of the
   living human brain measured after a single inhalation of positron
   emitting oxygen. J Cereb Blood Flow Metab. 1992;12:179-192.
See also: imgflow, imgdelay, fitdelay, imgcbv, fit_h2o, imgcalc
Keywords: image, modelling, perfusion, blood flow, radiowater, mask