RATIONALE AND OBJECTIVES. Perflubron, or perfluorooctylbromide, is an
effective ultrasound and computed tomography contrast agent in a lecit
hin emulsion form. The authors studied acoustical properties of perflu
bron emulsion in static human and flowing porcine blood for concentrat
ions from 0% to 30% weight per volume. METHODS. Propagation velocity (
c), the intensity attenuation coefficient (mu), density (rho), and par
ticle size were measured directly. Because the backscatter of flowing
blood is dependent on shear rate, relative echogenicity was measured a
s a function of perflubron concentration in whole porcine blood, in a
laminar flow system, at shear rates of 16.0 to 68.5 sec-1 for real-tim
e sector scanner images obtained at 7.5 MHz. RESULTS. Neat perflubron
is a colorless liquid with density of 1.93 g . mL-1 and velocity of 63
0 m . sec-1. The following values were obtained at 4.7 MHz in static h
uman blood (hematocrit 44%) at expected human in vivo blood concentrat
ions of 3.1% perflubron versus pure human blood: rho = 1.11 versus 1.0
5 g . mL-1, c = 1,480 versus 1,576 m . sec-1, mu = 1.00 versus 0.36 dB
. cm-1. The mean echogenicity of whole porcine blood increased substa
ntially with perflubron concentration and was inversely proportional t
o blood shear rate. CONCLUSION. Adding 3.1% concentration of perflubro
n increased image echogenicity at all shear rates studied, ranging fro
m 70% at 68.5 sec-1 (16.3 cm . sec-1) up to 180% at 16.0 sec-1 (3.8 cm
. sec-1). Perflubron enhancement of blood is marked and demonstrates
shear rate dependence like that of whole blood.