Setting simulation parameters
Model parameters can be based on population means from previous studies.
Although PET studies may not be routinely analyzed using compartmental models, compartmental models are usually required in simulations, and therefore the existing data need to be re-analyzed with compartmental models if necessary. Medians of parameter estimates from a number of subjects is preferred over means, because outliers in parameter estimates may lead to biased means.
Examples of other information needed in simulations:
- Vascular volume fraction
- Regional hematocrit
- Ratio of grey and white matter blood flow is 2.8 ± 0.35 (Østergaard et al., 1999)
- Water content (%): plasma 93-95 (mean 94), blood 80.5-80.8, RBC 63,
brain 76.3-78.5 (mean 77.4),
skeletal muscle 68.9-80.3 (mean 79),
kidneys 76 (Reference Man);
adipose tissue 11.4 - 30.5% (Duck 1990)
Alternatively, Hald (1946) measured that water content in human plasma is 0.93 ml/ml and in RBC 0.72 ml/ml, then human RBC to plasma water content ratio is 0.77 ml/ml
- Specific gravity (g ml-1): plasma 1.0266; blood 1.058; brain 1.04; skeletal muscle 1.04; adipose tissue 0.916; kidneys 1.06; liver 1.08 (Reference Man)
- Rat: brain blood flow, volume and hematocrit (Cremer and Seville, 1983)
Cremer JE, Seville MP. Regional brain blood, blood volume, and haematocrit values in the adult rat. J Cereb Blood Flow Metab. 1983; 3: 254-256.
Duck FA. Physical properties of tissue. Academic Press, London (1990), pp 320-328.
Hald PM. Notes on the determination and distribution of sodium and potassium in cells and serum of normal human blood. J Biol Chem. 1946; 163: 429-434.
ICRP Publication 23, Reference Man: Anatomical, Physiological, and Metabolic Characteristics, International Commission on Radiological Protection, Pergamon Press, New York (1975).
Østergaard L, Chesler DA, Weisskoff RM, Sorensen AG, Rosen BR. Modeling cerebral blood flow and flow heterogeneity from magnetic resonance residue data. J Cereb Blood Flow Metab. 1999; 19: 690-699.
Created at: 2010-09-20
Updated at: 2018-04-04
Written by: Vesa Oikonen