## lhsol - tpcclib 0.7.3 © 2019 by Turku PET Centre

```Fitting of full or reduced compartmental model to plasma and tissue
time-activity curves (PTAC and TTAC) to estimate the model parameters.

____        ____        ____        ____
| Cp |--K1->| C1 |--k3->| C2 |--k5->| C3 |  compartments in series (s)
|____|<-k2--|____|<-k4--|____|<-k6--|____|

____        ____
____       |    |--k3->| C2 |            compartments in parallel (p)
|    |--K1->|    |<-k4--|____|
| Cp |      | C1 |       ____
|____|<-k2--|    |--k5->| C3 |
|____|<-k6--|____|

Compartmental models are transformed into general linear least squares
functions (1, 2, 3, 4), which are solved using Lawson-Hanson linear
least-squares algorithms (5). Note that rate constants and macroparameters
are represented per volume (as measured by PET) including vascular volume.

Usage: lhsol [options] PTAC TTAC fittime results

Options:
-model=<k1 | k2 | k3 | k4 | k5s | k6s | k5p | k6p>
representing the following compartmental model settings:
k1 (for assuming k2=k3=k4=k5=k6=0)
k2 (for assuming k3=k4=k5=k6=0)
k3 (for assuming k4=k5=k6=0)
k4 (for assuming k5=k6=0); default
k5s (for assuming k6=0 and compartments in series)
k6s (compartments in series)
k5p (for assuming k6=0 and compartments in parallel)
-Vp=<ignored|fitted>
Vascular volume is ignored (default) or fitted; note that PTAC is
assumed to represent vascular blood curve.
-w1 | -wf
Sample weights are set to 1 (-w1) or to frame lengths (-wf);
by default weights in TTAC file are used, if available.
-svg=<Filename>
Fitted and measured TACs are plotted in specified SVG file.
-fit=<Filename>
Fitted regional TTACs are written in specified file.
-lp=<Filename>
Parameters of linear model are saved in specified file.
-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.

References:
1. Blomqvist G. On the construction of functional maps in positron emission
tomography. J Cereb Blood Flow Metab 1984;4:629-632.
2. Gjedde A, Wong DF. Modeling neuroreceptor binding of radioligands
in vivo. In: Quantitative imaging: neuroreceptors, neurotransmitters,
and enzymes. (Eds. Frost JJ, Wagner HM Jr). Raven Press, 1990, 51-79.
3. Oikonen V. Multilinear solution for 4-compartment model:
I. Tissue compartments in series.
http://www.turkupetcentre.net/reports/tpcmod0023.pdf
4. Oikonen V. Multilinear solution for 4-compartment model:
II. Two parallel tissue compartments.
http://www.turkupetcentre.net/reports/tpcmod0024.pdf
5. Lawson CL & Hanson RJ. Solving least squares problems.
Prentice-Hall, 1974.