Tissue mimicking materials for the detection of prostate cancer using shear wave elastography: A validation study

Abstract

Purpose: Quantification of stiffness changes may provide important diagnostic information and aid in the early detection of cancers. Shear wave elastography is an imaging technique that assesses tissue stiffness using acoustic radiation force as an alternate to manual palpation reported previously with quasistatic elastography. In this study, the elastic properties of tissue mimicking materials, including agar, polyacrylamide (PAA), and silicone, are evaluated with an objective to determine material characteristics which resemble normal and cancerous prostate tissue. Methods: Acoustic properties and stiffness of tissue mimicking phantoms were measured using compressional mechanical testing and shear wave elastography using supersonic shear imaging. The latter is based on the principles of shear waves generated using acoustic radiation force. The evaluation included tissue mimicking materials (TMMs) within the prostate at different positions and sizes that could mimic cancerous and normal prostate tissue. Patient data on normal and prostate cancer tissues quantified using biopsy histopathology were used to validate the findings. Pathologist reports on histopathology were blinded to mechanical testing and elastographic findings.

Predicting the growth of nanoscale nuclei by histotripsy pulses

“…The pressure at the bubble wall, p w , is defined in terms of the properties of the viscoelastic medium: $$p_{\mathrm{w}}=\left(P_0+\frac{2\sigma }{R_0}\right){\left(\frac{R_0}{R}\right)}^{3\kappa }-\frac{2\sigma }{R}-\frac{4\mu \stackrel{.}{R}}{R}-\frac{4G}{3}\left[1-{\left(\frac{R_0}{R}\right)}^3\right]-P_0-p_{\text{AC}}false(tfalse)$$ where P 0 is the ambient pressure (0.1 MPa), R 0 is the initial radius of the air-filled cavitation nucleus. Unless otherwise specified, the following values of the medium properties were used: surface tension, σ = 0.056 N m −1 (Holland and Apfel 1989, Church et al 2015), dynamic viscosity, μ = 0.005 kg m −1 s −1 (Holland and Apfel 1989, Church et al 2015), and shear modulus, G = 30 kPa (Cao et al 2013). …”

Polyvinyl chloride as a multimodal tissue‐mimicking material with tuned mechanical and medical imaging properties

“…[1][2][3][4] In medical research, tissuemimicking materials play important roles as idealized tissue models to evaluate clinical devices, procedures, and systems, achieving more repeatable results in experiments than real tissues due to their stability, consistency, and uniform properties. [5][6][7] For instance, medical imaging researchers often utilize tissue-mimicking materials to calibrate equipment and develop new imaging methods. 5 A material that can be used for two or more imaging modalities is said to be multimodal.…”

“…17 In ultrasound imaging technology development, tissuemimicking materials are usually created with similar acoustic properties (i.e., speed of sound, acoustic attenuation, and acoustic impedance) to those of the soft tissues of interest. [5][6][7][8] Examples of ultrasound phantoms include agar based wall-less vessel phantoms for Doppler flow measurements, 18 mixed agar and gelatin phantoms for elasticity imaging, 19 and anthropomorphic phantoms made from multiple tissue-mimicking materials for medical training. 20 For magnetic resonance imaging (MRI) phantoms, tissue-mimicking materials must have physiologically relevant relaxation times, denoted T 1 and T 2 as the rate at which the longitudinal and the transverse magnetization vectors recover and decay, respectively.…”

Quantitative elasticity measurement of urinary bladder wall using laser-induced surface acoustic waves

“…Elastography has become an attractive topic in the biomedical field over the past decade; it employs different imaging modalities to evaluate tissue biomechanical properties from the tissue response generated by different mechanical stimulations, e.g., compression and vibration. Ultrasound-based elastography [12][13][14][15][16] and magnetic resonance imaging-(MRI-) based elastography [17][18][19][20] have been widely studied and applied for the diagnosis and evaluation of treatment responses in many diseases, e.g., breast cancer, cardiological disorders, and liver fibrosis staging. There have been preliminary studies of the application of ultrasound elastography and MR elastography to determining bladder elasticity [8,21,22].…”