Towards an ideal blood analogue for Doppler ultrasound phantoms

Abstract

If a phantom is to produce Doppler spectral waveforms accurately matching those that would be obtained in vivo, it is necessary to use a fluid that behaves like blood in vivo, both acoustically and rheologically. The use of blood itself is undesirable and an analogue is required. Blood exhibits non-Newtonian behaviour as a result of aggregation of erythrocytes at low shear rates. This behaviour affects flow not only in sub-millimetre diameter vessels, but also in large scale structures. An alternative to blood is described that uses finely powdered nylon suspended in a mixture of glycerol and water. The nylon particles used have dimensions and density close to those of erythrocytes and they aggregate at low shear rates to give non-Newtonian behaviour. Viscosity may be varied over a wide range by the addition of liquid detergent. Consideration is given to the importance of haematocrit in modelling pulsatile and disturbed flows as it affects the haemodynamics of flow and the backscattered power of an ultrasound beam. This adaptable blood analogue is suitable for use in models of both large structures and fine vessels.

Viscoelasticity of blood and viscoelastic blood analogues for use in polydymethylsiloxane in vitro models of the circulatory system

“…Additionally, the rheological properties of blood at room temperature are different from those at body temperature 15 leading to an additional complication in setting up experiments. 16 For these reasons, the development of reliable blood analogues and the study of their flow characteristics are of great importance.…”

A review of Doppler ultrasound quality assurance protocols and test devices

“…More recently, the use of vessel mimicking materials has become more prominent [24e26]. Several types of BMF have been developed [27,28], with the one most closely matching real blood developed as part of an European Commission project [11,12]. The Medical Physics Department in St George's Hospital, London, U.K. developed a flow phantom largely based on the International Electrotechnical Comission (IEC) 61685 recommendations [29] which also included extra targets for the assessment of parameters such as Doppler temporal resolution; however, there are limited papers outlining this work despite the routine use of the system for Doppler ultrasound quality control [30].…”

A theoretical and experimental analysis of the received signal from disturbed blood flow

“…2 ) Blood Mimicking Fluid: As in [2], we have chosen to develop and study a blood analogue with properties at 22°C which are matched to those of blood at 37"C, although with a higher backscattered power. For this particular study, the increase in the backscattered power of 15.5 dB for the blood mimicking fluid in comparison with human blood was desirable.…”

“…The density of the resulting solution is 1027 kg/m3, the dynamic viscosity of the solution is 0.004 kg/(m .S) and the speed of sound is 1545 m/s. We have also suspended Orgasol 3501 ex D in glycerol, water and detergent, as described in [2], [ 5 ] . The resulting data from Orgasol suspended in the two fluids using the stenotic vessel phantoms had identical statistical properties.…”

“…One difference noted using Orgasol at a 45% volume concentration as opposed to Sephadex at a 25% volume Concentration was a small increase in the length of the correlated signalfiom a vortex at a flow rate of 5 mLis. Both Sephadex and Orgasol have previously been shown to produce a scattered wave with a Doppler spectrum which is similar to that of blood, although the scattered power is higher [l], [2].…”