An anthropomorphic tissue-mimicking phantom of the oesophagus for endoscopic ultrasound

The development and acoustical characterisation of a range of novel agar-based tissue mimicking material (TMMs) for use in clinically relevant, quality assurance (QA) and anthropomorphic breast phantoms are presented. The novel agar-based TMMs described in this study are based on a comprehensive, systematic variation of the ingredients in the International Electrotechnical Commission (IEC) TMM. A novel, solid fat-mimicking material was also developed and acoustically characterised. Acoustical characterisation was carried out using an in-house scanning acoustic macroscope at low (7.5 MHz) and high frequencies (20 MHz), using the pulse-echo insertion technique. The speeds of sound range from 1490 to 1570 m. s -1 , attenuation coefficients range from 0.1 to 0.9 dB. cm -1 . MHz -1 and relative backscatter ranges from 0 to -20 dB. It was determined that tissues can be mimicked in terms of independently controllable speeds of sound and attenuation coefficients. These properties make these novel TMMs suitable for use in clinically relevant QA and anthropomorphic phantoms, and would potentially be useful for other high frequency applications such as intra-vascular and small animal imaging.

Section: Discussionsupporting

confidence: 70%

Novel Tissue Mimicking Materials for High Frequency Breast Ultrasound Phantoms

Cannon¹,

Fagan

Browne³

2011

“…The polynomial fit was found to be of the form 0.40 f + 0.0076 f 2 and agreed well with the earlier measurements in the frequency range of 2–7 MHz (Browne et al. 2003) and 6–15 MHz (Inglis et al. 2006) and 17–23 MHz (Brewin et al.…”

Section: Discussionmentioning

confidence: 99%

“…It has been widely used, for example in flow phantom design (Ramnarine et al. 2001), in anthropomorphic phantoms (Inglis et al. 2006) and in breast phantoms (Cannon et al.…”

Section: Introductionmentioning

confidence: 99%

The Speed of Sound and Attenuation of an IEC Agar-Based Tissue-Mimicking Material for High Frequency Ultrasound Applications

Sun

Pye

Browne³

et al. 2012

This study characterized the acoustic properties of an International Electromechanical Commission (IEC) agar-based tissue mimicking material (TMM) at ultrasound frequencies in the range 10–47 MHz. A broadband reflection substitution technique was employed using two independent systems at 21°C ± 1°C. Using a commercially available preclinical ultrasound scanner and a scanning acoustic macroscope, the measured speeds of sound were 1547.4 ± 1.4 m∙s−1 and 1548.0 ± 6.1 m∙s−1, respectively, and were approximately constant over the frequency range. The measured attenuation (dB∙cm−1) was found to vary with frequency f (MHz) as 0.40f + 0.0076f2. Using this polynomial equation and extrapolating to lower frequencies give values comparable to those published at lower frequencies and can estimate the attenuation of this TMM in the frequency range up to 47 MHz. This characterisation enhances understanding in the use of this TMM as a tissue equivalent material for high frequency ultrasound applications.

“…Finally, the acoustic properties of the phantom were intermediate between water and soft tissue. The sound speed can be increased from ~1500 m/s to the expected soft tissue value of 1540 m/s by addition of a small quantity of glycerol (Inglis et al 2006). Attenuation can also be increased with BSA.…”

Section: Discussionmentioning

confidence: 99%

A Tissue Phantom for Visualization and Measurement of Ultrasound-Induced Cavitation Damage

Maxwell

Wang

Yuan

et al. 2010

116

130

Many ultrasound studies involve the use of tissue-mimicking materials to research phenomena invitro and predict in-vivo bioeffects. We have developed a tissue phantom to study cavitationinduced damage to tissue. The phantom consists of red blood cells suspended in an agarose hydrogel. The acoustic and mechanical properties of the gel phantom were found to be similar to soft tissue properties. The phantom's response to cavitation was evaluated using histotripsy. Histotripsy causes breakdown of tissue structures by generation of controlled cavitation using short, focused, high-intensity ultrasound pulses. Histotripsy lesions were generated in the phantom and kidney tissue using a spherically focused 1-MHz transducer generating 15 cycle pulses at a pulse repetition frequency of 100 Hz with a peak negative pressure of 14 MPa. Damage appeared clearly as increased optical transparency of the phantom due to rupture of individual red blood cells. The morphology of lesions generated in the phantom was very similar to that generated in kidney tissue, at both macroscopic and cellular levels. Additionally, lesions in the phantom could be visualized as hypoechoic regions on a B-Mode ultrasound image, similar to histotripsy lesions in tissue. High speed imaging of the optically-transparent phantom was used to show that damage coincides with the presence of cavitation. These results indicate that the phantom can accurately mimic the response of soft tissue to cavitation and provide a useful tool for studying damage induced by acoustic cavitation.