Power-law kinetics of tracer washout from physiological systems.
Recent studies suggest that the tail of the washout of tracer-labeled substances from physiological systems can exhibit power-law behavior. In this work we develop a theoretical interpretation of the power-law behavior of the flow-limited washout of tracer-labeled water from the myocardium. Using minimal assumptions concerning the complicated structure of the coronary network we show that the washout from a heterogeneous flow system is given by h(t) approximately equal to A x p1 (V/t)(-beta), where beta is close to 3, p1 is the probability density of flows through the system, V is a constant volume associated with each pathway, and A is a constant. This prediction fits observed power-law washout behavior of tracer water in the heart. This theory is general enough to lead us to speculate that close examination of transport in other heterogeneity-perfused systems is likely to reveal similar power-law behavior.
Beard
D A
DA
Center for Bioengineering, University of Washington, Seattle 98195-7962, USA.
Bassingthwaighte
J B
JB
D000818:Animals; D015982:Bias; D001783:Blood Flow Velocity / Q000502:physiology*; D003326:Coronary Circulation / Q000502:physiology*; D020342:Finite Element Analysis; D017709:Fractals; D006801:Humans; D008833:Microcirculation / Q000502:physiology*; D008955:Models, Cardiovascular; D016011:Normal Distribution; D011237:Predictive Value of Tests; D011849:Radioactive Tracers; D015203:Reproducibility of Results
D011849:Radioactive Tracers