Can blood flow in separate small tubes be quantitatively assessed by high-resolution laser Doppler imaging?

A method is suggested for quantitative flow assessment of whole-blood perfusing tubes with diameters in the range from 500 mu m to 1.5 mm, for velocities below 9 mm s(-1). The algorithm is based both on the Doppler broadening of backscattered laser light and the magnitude of the diameter of the perfused tube. A bandwidth-modified high-resolution laser Doppler perfusion imaging system is used to record the Doppler broadening. A flow model, consisting of a linearly narrowing tube (inner diameter 620- 1330 mu m), is connected to a precision infusion pump and perfused by human whole blood of volume flows ranging from 0 to 6.6 mm(3) s(-1). Empirical data are fitted into a regression model, and the parameters of the algorithm can be determined, resulting in a correlation coefficient of 0.975 between the predicted and true volume flows; Using this algorithm, volume flows in tubes of inner diameters of 500 mu m, 750 mu m and 1.4 mm are predicted, with accuracies corresponding to correlation coefficients of 0.994, 0.993 and 0.996.