imgbfh2o 0.2.0 © 2013 by Turku PET Centre
Estimation of rate constants K1, k2 and Va from dynamic PET image in
ECAT 6.3, ECAT 7.x, NIfTI-1, or Analyze 7.5 file format using
one-tissue compartment model (1), solved using the basis function
approach (2, 3).
When applied to dynamic [O-15]H2O studies, the resulting K1 image
equals perfusion (blood flow) image. K1 image can be divided by tissue
density (g/mL) (option -density) and multiplied by 100 (option -dl)
to achieve the blood flow image in units (mL blood)/((100 g tissue) * min).
When applied to dynamic [O-15]O2 brain studies, the resulting K1 image
can be converted to oxygen consumption image by multiplying it by
arterial oxygen concentration [4] (ml O2 / dL blood) to get the
parametric image in units mL O2 / ((100 ml tissue) * min).
The model assumptions hold only when oxygen consumption is 1-6.7
ml O2/(100g * min) and fit time is set to 300 s or less [4].
Parameters:
1) Blood TAC file (corrected for decay and delay, times in seconds!)
2) Dynamic image file (corrected for decay)
3) Fit time (s)
4) Parametric K1 (flow) image file
General options:
-ml or -dl
Units in flow and Va images will be given per mL or per dL,
respectively. By default, units are per mL.
-density[=<value>]
With option -density the flow is calculated per gram or 100g tissue.
Tissue density can be changed from the default 1.04 g/ml.
-Vd=<filename>
Parametric K1/k2 (Vd, apparent p) image is saved.
-k2=<filename>
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 partiton coefficient of water in tissue.
-Va=<filename>
Parametric Va image is saved.
Set -Va=0, if Va=0 is assumed (pre-corrected); otherwise Va is fitted.
-wss=<filename>
Weighted sum-of-squares are written in specified image file.
-thr=<threshold%>
Pixels with AUC less than (threshold/100 x input AUC) are set to zero;
default is 0%
-h or --help
Print this message and exit.
--version or --build
Print software build information and exit.
--silent
Program works silently, printing only error and warning messages.
--verbose
Program prints more information about what it is doing.
Options for setting basis functions:
-k2min=<Min k2> and -k2max=<Max k2>
Enter the minimum and maximum k2 in units ml/(ml*min).
-fmin=<Min K1> and -fmax=<Max K1>
Enter the minimum and maximum perfusion value; defaults are
0.005 and 4.0 ml/(ml*min), respectively.
-pmin=<Min p> and -max=<pmax>
Enter the minimum and maximum value for apparent partition coefficient
for water; defaults are 0.3 and 1.0 ml/ml, respectively.
-nr=<value>
Set number of basis functions; default is 500, minimum 100.
-bf=<filename>
Basis function curves are written in specified file.
-err=<filename>
Pixels with their k2 in its min or max value (calculated from min and
max K1 and p values) in the specified imagefile with values 1 and 2,
respectively, others with value 0.
Example 1. Calculation of perfusion and arterial blood volume image,
stopping fit at 180 s:
imgbfh2o -Va=s2345va.img s2345abfit.kbq s2345dy1.v 180 s2345flow.v
By default, the units of pixel values in the blood flow (K1) image is
(mL blood)/((mL tissue) * min), in Vd image (mL blood)/(mL tissue),
in k2 image 1/min, and in Va image (mL blood/mL tissue),
but the blood flow and Va units can be changed with above listed options.
References:
1. Lammertsma AA, Jones T. J Cereb Blood Flow Metab. 1983;3:416-424.
2. Gunn RN et al. NeuroImage 1997;6:279-287.
3. Boellaard R et al. Mol Imaging Biol. 2005;7:273-285.
4. Ohta S, et al. J Cereb Blood Flow Metab. 1992;12:179-192.
See also:
imgflow,
arlkup,
regbfh2o,
fit_h2o,
ecatunit,
fitdelay,
imgcbv
Keywords: image, modelling, perfusion, radiowater, basis function method
This program comes with ABSOLUTELY NO WARRANTY. This is free software, and
you are welcome to redistribute it under GNU General Public License.