Contrast medium assisted fluid flow measurements

Abstract

In this paper the development and evaluation of two new approaches for ultrasound time-domain fluid flow measurements by tracking echoes scattered by a contrast agent following injection of a bolus of the contrast agent are described. Their feasibility was investigated by measuring velocity or velocity profile of blood flowing in a mock circulatory loop in vitro. Measurements were made with a one transducer intravessel approach and a two transducer extravessel approach. A hybrid cluster or vector cross-correlation method was used to track the motion of the scatterers in the two transducer time-domain method. This cluster or vector cross correlation method was developed to reduce the ambiguity resulted from misregistration which is a common problem in target tracking by correlating signal patterns. The experimental results show a good agreement between the measured data and those estimated from timing the volume. Although the discussions given in this paper pertain only to blood flow measurements, there is no reason to indicate that these approaches can not be used for fluid flow measurements in an industrial environment if suitable contrast agents can be developed.

Characterization of Blood Properties from Coagulating Blood of Different Hematocrits Using Ultrasonic Backscatter and Attenuation

“…6). Depending on the size, shape, concentration, density, and other elastic properties of the scatterers in a biological tissue, [11][12][13] ultrasonic backscattered signals might be more feasible to detect the local variation of scatterers in the microstructure such as the fibrin fibers than that of the ultrasonic attenuation. On the other hand, the increase of attenuation associated with clot formation could be due to biochemical interactions among constituents of the blood.…”

“…Due to low cost and real-time capabilities, other alternative feasibility studies with ultrasound techniques were explored, that included spectroscopy, 7) acoustic streaming, 8,9) and ultrasonic shear wave. 10) Furthermore, several previous studies have been carried out with ultrasonic parameters to characterize blood properties [11][12][13][14] and during coagulation. [15][16][17][18][19][20] Nevertheless, most of these studies on blood coagulation were achieved only from blood samples at a normal hematocrit which moreover could be adjusted to a substantial range depending on pathological conditions of a patient.…”

Effects of Sub-100 nm Platinum Metal Particle on the Acoustic Attenuation Properties of Silicone Rubber Lens for Medical Array Probe

“…Density was measured by the water-immersion method. Longitudinal wave velocity and attenuation were measured by a reflection method in water using a 5 MHz transducer at 25 C. 10,11)…”

The Effect of Kinetic Properties on Statistical Variations of Ultrasound Signals Backscattered from Flowing Blood

“…1) Recently, properties of RBC aggregation associated several factors with blood flows have been studied by ultrasound techniques due to their real-time and noninvasive capabilities. [2][3][4][5] The variation of scatterer size in the flowing blood associated with the formation of RBC aggregation may be sensitively detected by ultrasonic backscattering due to that it is scatterer size dependent. Consequently, several previous studies have applied ultrasonic backscattering to correlate that the formation of RBC aggregation is affected by the shear rate, hematocrit, and fibrinogen concentration in the flowing blood.…”