Ren. Shehada et al., ULTRASOUND METHODS FOR INVESTIGATING THE NON-NEWTONIAN CHARACTERISTICS OF WHOLE-BLOOD, IEEE transactions on ultrasonics, ferroelectrics, and frequency control, 41(1), 1994, pp. 96-104
The development and evaluation of new techniques for investigating the
non-Newtonian characteristics of blood are described. Ultrasound B-mo
de imaging (7 MHz) was used to measure simultaneously the echogenicity
and velocity profiles of 28% hematocrit porcine whole blood. Measurem
ents were made at various axial locations in a large diameter (D = 2.5
4 cm) long (> GOD) tube, under steady flow conditions. A block matchin
g (correlation) technique between successive digitized images was used
to determine the velocity profiles, and from these, shear rate profil
es were calculated. The optimal block dimensions were found to be depe
ndent on the magnitude and direction of the flow shear rate. Echogenic
ity profiles were determined from ensemble averaged images. It is show
n how such profiles in combination with the corresponding shear rate p
rofiles enables information to be obtained concerning the dependence o
f aggregation on shear rate. Pulsed Doppler ultrasound (20 MHz) was al
so used to measure the velocity and backscattered power profiles at 60
D from the tube entrance. Velocity profiles measured using B-mode were
in good agreement with those obtained using both pulsed Doppler and m
agnetic resonance imaging and mean velocity errors of less that 5% wer
e achieved.