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. See also: fitk4, fitk5, patlak, logan, imglhdv, fitdelay, taccbv Keywords: TAC, modelling, compartmental model, LLSQ