Determination of vascular permeability coefficients under slow luminal filling

This Communication describes a method to obtain the permeability product (permeability coefficient normalized by vascular dimensions) from time-lapse intensity data for which the introduction of labeled solute into the vasculature does not occur at a sharply defined time. This method has an error of ~ 10% across a wide range of filling times and noise levels, and is particularly well-suited for situations in which the permeability coefficient is greater than 10− 6 cm/s. We show that it is applicable whether the increase in vascular solute concentration is sustained or transient.