ReviewA Review of Tissue Substitutes for Ultrasound Imaging
Introduction
Tissue phantoms have been used for characterization and calibration of ultrasound imaging systems since the 1960s. Phantoms are also used to compare the performance of ultrasound systems for training of ultrasound technicians, for comparison to computer models and to assist in the development of new ultrasound transducers, systems or diagnostic techniques. The advantage of phantoms is that idealized tissue models can be constructed with well-defined acoustic properties, dimensions and internal features, thereby simplifying and standardizing the imaging environment.
Phantoms are composed of tissue-mimicking materials, with the majority of phantoms having a simple homogeneous internal structure. Simple or complex targets are sometimes embedded within phantoms to mimic internal structures or to serve as characterization targets. Phantoms that accurately mimic heterogeneous organs or organ systems are often referred to as anthropomorphic phantoms. The term tissue substitute encompasses both phantoms and tissue-mimicking materials.
Phantoms and anthropomorphic phantoms are available commercially, mimicking many tissues organs and organ systems. Commercial phantoms range in price from hundreds to thousands of dollars and are often preferred for training and calibration of ultrasound systems. However, commercial phantoms are typically designed for broad markets and specific applications, and are not customizable. For this reason, customized design and fabrication of tissue phantoms is required for more specialized applications requiring tailored properties or dimensions, or when seeking to reduce cost.
This paper reviews many of the materials and techniques used to prepare both soft and hard tissue-mimicking materials and phantoms, focusing primarily on those developed for traditional ultrasound imaging rather than those developed specifically for elasticity imaging (elastography), Doppler (string phantoms) or alternate ultrasound techniques such as high-intensity focused ultrasound (HIFU). Many of the relevant acoustic properties and measurements are first discussed, followed by common materials and preparation techniques used to develop general soft tissue phantoms. The subsequent sections focus on the development of specific soft tissue phantoms and on the materials and techniques used to develop hard tissues phantoms. This paper is intended to allow the ultrasound researcher to better understand the advantages and disadvantages of various techniques and to select the appropriate approach for their own work.
Section snippets
Phantom and Tissue Properties
Tissue substitutes used in ultrasonography must possess acoustic properties near those of the tissues of interest, with the most critical acoustic properties of soft tissue substitutes being the compressional speed of sound, characteristic acoustic impedance, attenuation, backscattering coefficient and nonlinearity parameter (ICRU 1998). The most relevant acoustic properties for hard tissues include the compressional and shear wave speeds of sound, characteristic acoustic impedance and
Soft Tissue-Mimicking Materials
Soft tissues are composed of muscles, tendons, ligaments, fascia, fat, fibrous tissue, synovial membranes, nerves and blood vessels. Although some soft tissue phantoms have been developed to include many of the components of soft tissues, the majority of tissue substitutes have modeled each tissue as isotropic, homogeneous materials. It is also often desirable to prepare homogeneous tissue substitutes that mimic the broader soft tissue environment rather than individual tissues or groups of
Soft Tissue Phantoms
Many of the soft tissue substitute preparation techniques described before have been modified and tailored to mimic specific tissues or organs. Some have combined multiple techniques to develop phantoms or more realistic anthropomorphic phantoms. A sampling of the techniques used to mimic specific soft tissues and organs are provided.
Hard Tissue-Mimicking Materials and Phantoms
Hard tissues are mineralized tissues with a firm intercellular substance and include cortical bone, trabecular bone, dental enamel and dentin. Bone substitutes and phantoms have been developed primarily to evaluate and calibrate ultrasound systems designed specifically for detecting bone pathologies (Young et al., 1993, Clarke et al., 1994). Ultrasound imaging of teeth has not yet become clinically accepted, but has been the subject of various studies because of its ability to penetrate hard
Discussion and Conclusion
Many soft tissue-mimicking materials have been described that have a compressional speed of sound, density, attenuation and acoustic impedance within the measured range of soft tissues (Table 1, Table 2). The backscattering coefficient, nonlinearity parameter and shear wave speed of sound (in the case of hard tissue substitutes) have rarely been reported and therefore are not included in the tables. Agarose-based materials have been the most widely used and are very well characterized in the
Acknowledgment
Partial funding for this work provided by the Telemedicine and Advanced Technology Research Center (TATRC)/Department of Defense under award numbers W81XWH-07-1-0672 and W81XWH-07-1-0668.
References (103)
- et al.
Steady flow in a model of the human carotid bifurcation. Part I—flow visualization
J Biomech Eng
(1982) - et al.
The acoustic properties, centered on 20 MHz, of an IEC agar-based tissue-mimicking material and its temperature, frequency and age dependence
Ultrasound Med Biol
(2008) - et al.
Assessment of the acoustic properties of common tissue-mimicking test phantoms
Ultrasound Med Biol
(2003) - et al.
Gelatine-alginate complex gel: A new acoustically tissue-equivalent material
Ultrasound Med Biol
(1983) - et al.
A real vessel phantom for flow imaging: 3-D Doppler ultrasound of steady flow
Ultrasound Med Biol
(2001) - et al.
Tissue phantom for learning US-guided vascular punctures
J Vasc Interv Radiol
(2001) - et al.
Nonlinearity parameter for tissue-mimicking materials
Ultrasound Med Biol
(1999) - et al.
Evaluation of Doppler ultrasound for blood perfusion measurements
Ultrasound Med Biol
(1991) - et al.
In-vitro visualization of biopsy needles with ultrasound: A comparative study of standard and echogenic needles using an ultrasound phantom
Clin Radiol
(2001) - et al.
A comparison of the Doppler spectra from human blood and artificial blood used in a flow phantom
Ultrasound Med Biol
(1990)
Feasibility of Measuring Acoustic Streaming for Improved Diagnosis of Rhinosinusitis
Ultrasound Med Biol
Comparison of nonuniform rotational distortion between mechanical IVUS and OCT using a phantom model
Ultrasound Med Biol
Evaluation of tissue mimicking quality of tofu for biomedical ultrasound
Ultrasound Med Biol
Liquid or solid ultrasonically tissue-mimicking materials with very low scatter
Ultrasound Med Biol
Anthropomorphic breast phantoms for testing elastography systems
Ultrasound Med Biol
An anthropomorphic ultrasound breast phantom containing intermediate-sized scatterers
Ultrasound Med Biol
A versatile test-object for the calibration of ultrasonic Doppler flow instruments
Ultrasound Med Biol
Anatomical flow phantoms of the nonplanar carotid bifurcation, part II: experimental validation with Doppler ultrasound
Ultrasound Med Biol
Thickness sensitivity of ultrasound velocity in long bone phantoms
Ultrasound Med Biol
Assessment of the cortical bone thickness using ultrasonic guided waves: modelling and in vitro study
Ultrasound Med Biol
A pulsating coronary vessel phantom for two- and three-dimensional intravascular ultrasound studies
Ultrasound Med Biol
Evaluation of a breast biopsy phantom for learning freehand ultrasound-guided biopsy of the liver
Acad Radiol
The improvement and quantitative assessment of B-mode images produced by an annular array/cone hybrid
Ultrason Imaging
Construction and geometric stability of physiological flow rate wall-less stenosis phantoms
Ultrasound Med Biol
Doppler backscatter properties of a blood-mimicking fluid for Doppler performance assessment
Ultrasound Med Biol
A wall-less vessel phantom for Doppler ultrasound studies
Ultrasound Med Biol
A new technique for measuring the acoustic nonlinearity of materials using Rayleigh waves
NDT&E Int
Use of multiple acoustic wave modes for assessment of long bones: model study
Ultrasonics
Development of an example flow test object and comparison of five of these test objects, constructed in various laboratories
Ultrasonics
Noninvasive simultaneous assessment of wall shear rate and wall distension in carotid arteries
Ultrasound Med Biol
Ultrasound-induced heating in a foetal skull bone phantom and its dependence on beam width and perfusion
Ultrasound Med Biol
Review: absorption and dispersion of ultrasound in biological tissue
Ultrasound Med Biol
Ultrasound phantom for hands-on practice
Reg Anesth Pain Med
Estimation of liver tumor volume using a three-dimensional ultrasound volumetric system
Ultrasound Med Biol
Theoretical and experimental quantification of carotid plaque volume measurements made by three-dimensional ultrasound using test phantoms
Med Phys
Freehand elasticity imaging using speckle decorrelation rate
Acoust Imag
Assessment of the geometry of human finger phalanges using quantitative ultrasound in vivo
Osteoporos Int
Applications of laser-based ultrasonics to the characterization of the internal structure of teeth
J Acoust Soc Am
Performance tests of Doppler ultrasound equipment with a tissue and blood-mimicking phantom
J Ultrasound Med
Development of a prototype anthropomorphic ultrasound phantom: 1992 CIVCO/SDMS Innovation in Ultrasound Award
J Diagn Med Sonog
A new ultrasound tissue-equivalent material
Radiology
A phantom for quantitative ultrasound of trabecular bone
Phys Med Biol
Ultrasound crack detection in a simulated human tooth
Dentomaxillofac Radiol
Tissue mimicking materials for a multi-imaging modality prostate phantom
Med Phys
A real vessel phantom for imaging experimentation
Med Phys
Quantitative measurement of fetal blood flow using Doppler ultrasound
Br J Obstet Gynaecol
Estimation of blood velocity with high frequency ultrasound
IEEE Trans Ultrason Ferroelectr Freq Control
A geometrically accurate vascular phantom for comparative studies of x-ray, ultrasound, and magnetic resonance vascular imaging: Construction and geometrical verification
Med Phys
Characterization of PVA cryogel for intravascular ultrasound elasticity imaging
IEEE Trans Ultrason Ferroelectr Freq Control
Cited by (501)
A mm-sized acoustic wireless implantable neural stimulator based on a piezoelectric micromachined ultrasound transducer
2024, Sensors and Actuators B: ChemicalCharacterization of the concentration of agar-based soft tissue mimicking phantoms by impact analysis
2024, Journal of the Mechanical Behavior of Biomedical MaterialsAcoustoelectric materials & devices in biomedicine
2024, Chemical Engineering JournalSystematic quantification of differences in shear wave elastography estimates between linear-elastic and viscoelastic material assumptions
2024, Journal of the Acoustical Society of America