Acoustic characterization of tissue-mimicking materials for ultrasound perfusion imaging research.

Peiran Chen,Andreas M.A.O Pollet,Anastasiia Panfilova,Meiyi Zhou,Jaap M.J Den Toonder,Simona Turco,Massimo Mischi

doi:10.1016/j.ultrasmedbio.2021.09.004

Peiran Chen, Andreas M.A.O Pollet + Show 5 more

Open Access

https://doi.org/10.1016/j.ultrasmedbio.2021.09.004

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Abstract

Materials with well-characterized acoustic properties are of great interest for the development of tissue-mimicking phantoms with designed (micro)vasculature networks. These represent a useful means for controlled in-vitro experiments to validate perfusion imaging methods such as Doppler and contrast-enhanced ultrasound (CEUS) imaging. In this work, acoustic properties of seven tissue-mimicking phantom materials at different concentrations of their compounds and five phantom case materials are characterized and compared at room temperature. The goal of this research is to determine the most suitable phantom and case material for ultrasound perfusion imaging experiments. The measurements show a wide range in speed of sound varying from 1057 to 1616 m/s, acoustic impedance varying from 1.09 to 1.71×106 kg/m2s, and attenuation coefficients varying from 0.1 to 22.18 dB/cm at frequencies varying from 1 MHz to 6 MHz for different phantom materials. The nonlinearity parameter B/A varies from 6.1 to 12.3 for most phantom materials. This work also reports the speed of sound, acoustic impedance and attenuation coefficient for case materials. According to our results, polyacrylamide (PAA) and polymethylpentene (TPX) are the optimal materials for phantoms and their cases, respectively. To demonstrate the performance of the optimal materials, we performed power Doppler ultrasound imaging of a perfusable phantom, and CEUS imaging of that phantom and a perfusion system. The obtained results can assist researchers in the selection of the most suited materials for in-vitro studies with ultrasound imaging.

Highlights

Imaging and quantification of blood perfusion reveals a fundamental property of tissue that varies in many important physiological and pathological processes (Cosgrove and Lassau, 2010)
The measured speed of sound (SoS) is in the range from 1454 to 1512 m/s for agrarose, from 1420 to 1447 m/s for alginate, from 1495 to 1531 m/s for gelatin, from 1445 to 1538 m/s for PAA, from 1550 to 1616 m/s for polyvinyl alcohol (PVA), from 1529 to 1576 m/s for polyethylene glycol diacrylate (PEGDA) and from 1057 to 1081 m/s for PDMS
The SoS values for agarose, PAA, PVA and PDMS with several known density are available in literature for comparison

Summary

Introduction

Imaging and quantification of blood perfusion reveals a fundamental property of tissue that varies in many important physiological and pathological processes (Cosgrove and Lassau, 2010). As a variation of CFI, power Doppler (ultrasound angiography) is based on the power of the signal coherence that is estimated by autocorrelation over frames, improving the ability over standard CFI to image blood flow in smaller vessels (Szabo, 2014). CEUS provides real-time imaging of blood flow with the help of intravenously-injected ultrasound contrast agents (UCAs). These consist of gas-filled microbubbles encapsulated in a biocompatible shell with the size comparable to that of blood cells (Cosgrove, 2006). Thanks to their size, they behave as bloodpool agents and are suitable to assess blood flow

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