Rheolution Inc

Montréal, Canada

Rheolution Inc

Montréal, Canada

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Hadj Henni A.,University of Montréal | Hadj Henni A.,Rheolution Inc. | Schmitt C.,University of Montréal | Schmitt C.,Rheolution Inc. | And 5 more authors.
Journal of the Mechanical Behavior of Biomedical Materials | Year: 2011

With the emergence of new biomaterials and elastography imaging techniques, there is a need for innovative instruments dedicated to viscoelasticity measurements. In this work, we introduce a novel hyper-frequency viscoelastic spectroscopy (HFVS) technique dedicated to characterize soft media subjected to mid-to-very-high frequency stress ranges (or, equivalently, to probe short-to-very-short relaxation times). HFVS, which has been implemented in an analytical instrument performing non-contact measurements in less than 1 s between 10 and 1000 Hz, is a suitable tool to study viscoelasticity for bio-applications. In this context, HFVS has been compared to classical oscillatory rheometry on several classes of soft materials currently encountered in tissue repair, bioengineering and elastography imaging on a frequency range between 10 and 100 Hz. After having demonstrated the good correspondence between HFVS and rheometry, this study has been completed by exploring the sensitivity of HFVS to physicochemically induced variations of viscoelasticity. HFVS opens promising perspectives in the challenging field of biomaterial science and for viscoelasticity-based quality control of materials. © 2011 Elsevier Ltd.


Ekeom D.,University of Montréal | Henni A.,University of Montréal | Henni A.,Rheolution Inc. | Cloutier G.,University of Montréal
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control | Year: 2013

This work demonstrates, with numerical simulations, the potential of an octagonal probe for the generation of radiation forces in a set of points following a path surrounding a breast lesion in the context of dynamic ultrasound elastography imaging. Because of the in-going wave adaptive focusing strategy, the proposed method is adapted to induce shear wave fronts to interact optimally with complex lesions. Transducer elements were based on 1-3 piezocomposite material. Threedimensional simulations combining the finite element method and boundary element method with periodic boundary conditions in the elevation direction were used to predict acoustic wave radiation in a targeted region of interest. The coupling factor of the piezocomposite material and the radiated power of the transducer were optimized. The transducer's electrical impedance was targeted to 50 Ω. The probe was simulated by assembling the designed transducer elements to build an octagonal phased-array with 256 elements on each edge (for a total of 2048 elements). The central frequency is 4.54 MHz; simulated transducer elements are able to deliver enough power and can generate the radiation force with a relatively low level of voltage excitation. Using dynamic transmitter beamforming techniques, the radiation force along a path and resulting acoustic pattern in the breast were simulated assuming a linear isotropic medium. Magnitude and orientation of the acoustic intensity (radiation force) at any point of a generation path could be controlled for the case of an example representing a heterogeneous medium with an embedded soft mechanical inclusion. © 1986-2012 IEEE.


Ouared A.,University of Montréal | Montagnon E.,University of Montréal | Montagnon E.,Rheolution Inc. | Kazemirad S.,University of Montréal | And 3 more authors.
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control | Year: 2015

In remote dynamic elastography, the amplitude of the generated displacement field is directly related to the amplitude of the radiation force. Therefore, displacement improvement for better tissue characterization requires the optimization of the radiation force amplitude by increasing the push duration and/or the excitation amplitude applied on the transducer. The main problem of these approaches is that the Food and Drug Administration (FDA) thresholds for medical applications and transducer limitations may be easily exceeded. In the present study, the effect of the frequency used for the generation of the radiation force on the amplitude of the displacement field was investigated. We found that amplitudes of displacements generated by adapted radiation force sequences were greater than those generated by standard nonadapted ones (i.e., single push acoustic radiation force impulse and supersonic shear imaging). Gains in magnitude were between 20 to 158% for in vitro measurements on agar-gelatin phantoms, and 170 to 336% for ex vivo measurements on a human breast sample, depending on focus depths and attenuations of tested samples. The signal-to-noise ratio was also improved more than 4-fold with adapted sequences. We conclude that frequency adaptation is a complementary technique that is efficient for the optimization of displacement amplitudes. This technique can be used safely to optimize the deposited local acoustic energy without increasing the risk of damaging tissues and transducer elements. © 1986-2012 IEEE.


Ouared A.,University of Montréal | Montagnon E.,University of Montréal | Montagnon E.,Rheolution INC | Cloutier G.,University of Montréal
IEEE International Ultrasonics Symposium, IUS | Year: 2014

In remote dynamic elastography, amplitudes of generated displacement fields are directly related to the amplitude of the radiation force. Therefore, displacement improvement for better tissue characterization requires the optimization of the radiation force by increasing the push duration and/or the excitation amplitude of the transducer. The main problem of this approach is that the Food and Drug Administration (FDA) thresholds for medical applications, and transducer limitations may be easily exceeded. In the present study, the effect of the frequency used for the generation of radiation force on the amplitude of the displacement field is investigated. The aim is to apply the adaptive radiation force to increase the displacement amplitude. We found that amplitudes of displacements generated by adapted radiation force sequences are greater than those generated by non-adapted ones. The obtained gains were between 20% and 158% depending on the focus depths and the attenuation of the tested phantom. The signal to noise ratio was also improved by more than four times. We conclude that frequency adaptation is a complementary technique that may be used for the optimization of displacement amplitude. This technique can be used safely to optimize the deposited local acoustic energy, without increasing the risk of damaging tissues and transducers. © 2014 IEEE.


Montagnon E.,University of Montréal | Hadj-Henni A.,University of Montréal | Hadj-Henni A.,Rheolution Inc. | Schmitt C.,University of Montréal | And 2 more authors.
IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control | Year: 2014

With the purpose of assessing localized rheological behavior of pathological tissues using ultrasound dynamic elastography, an analytical shear wave scattering model was used in an inverse problem framework. The proposed method was adopted to estimate the complex shear modulus of viscoelastic spheres from 200 to 450 Hz. The inverse problem was formulated and solved in the frequency domain, allowing assessment of the complex viscoelastic shear modulus at discrete frequencies. A representative rheological model of the spherical obstacle was determined by comparing storage and loss modulus behaviors with Kelvin¿Voigt, Maxwell, Zener, and Jeffrey models. The proposed inversion method was validated by using an external vibrating source and acoustic radiation force. The estimation of viscoelastic properties of three-dimensional spheres made softer or harder than surrounding tissues did not require a priori rheological assumptions. The proposed method is intended to be applied in the context of breast cancer imaging. © 2014 IEEE.


Ouared A.,University of Montréal | Montagnon E.,University of Montréal | Montagnon E.,Rheolution Inc. | Cloutier G.,University of Montréal
Physics in Medicine and Biology | Year: 2015

A method based on adaptive torsional shear waves (ATSW) is proposed to overcome the strong attenuation of shear waves generated by a radiation force in dynamic elastography. During the inward propagation of ATSW, the magnitude of displacements is enhanced due to the convergence of shear waves and constructive interferences. The proposed method consists in generating ATSW fields from the combination of quasi-plane shear wavefronts by considering a linear superposition of displacement maps. Adaptive torsional shear waves were experimentally generated in homogeneous and heterogeneous tissue mimicking phantoms, and compared to quasi-plane shear wave propagations. Results demonstrated that displacement magnitudes by ATSW could be up to 3 times higher than those obtained with quasi-plane shear waves, that the variability of shear wave speeds was reduced, and that the signal-to-noise ratio of displacements was improved. It was also observed that ATSW could cause mechanical inclusions to resonate in heterogeneous phantoms, which further increased the displacement contrast between the inclusion and the surrounding medium. This method opens a way for the development of new noninvasive tissue characterization strategies based on ATSW in the framework of our previously reported shear wave induced resonance elastography (SWIRE) method proposed for breast cancer diagnosis. © 2015 Institute of Physics and Engineering in Medicine.


Montagnon E.,University of Montréal | Hadj-Henni A.,University of Montréal | Hadj-Henni A.,Rheolution Inc | Schmitt C.,University of Montréal | And 2 more authors.
Physics in Medicine and Biology | Year: 2013

This paper presents a semi-analytical model of shear wave scattering by a viscoelastic elliptical structure embedded in a viscoelastic medium, and its application in the context of dynamic elastography imaging. The commonly used assumption of mechanical homogeneity in the inversion process is removed introducing a priori geometrical information to model physical interactions of plane shear waves with the confined mechanical heterogeneity. Theoretical results are first validated using the finite element method for various mechanical configurations and incidence angles. Secondly, an inverse problem is formulated to assess viscoelastic parameters of both the elliptic inclusion and its surrounding medium, and applied in vitro to characterize mechanical properties of agar-gelatin phantoms. The robustness of the proposed inversion method is then assessed under various noise conditions, biased geometrical parameters and compared to direct inversion, phase gradient and time-of-flight methods. The proposed elastometry method appears reliable in the context of estimating confined lesion viscoelastic parameters. © 2013 Institute of Physics and Engineering in Medicine.


Ouared A.,University of Montréal | Kazemirad S.,University of Montréal | Montagnon E.,University of Montréal | Montagnon E.,Rheolution Inc. | Cloutier G.,University of Montréal
Medical Physics | Year: 2016

Purpose: Different approaches have been used in dynamic elastography to assess mechanical properties of biological tissues. Most techniques are based on a simple inversion based on the measurement of the shear wave speed to assess elasticity, whereas some recent strategies use more elaborated analytical or finite element method (FEM) models. In this study, a new method is proposed for the quantification of both shear storage and loss moduli of confined lesions, in the context of breast imaging, using adaptive torsional shear waves (ATSWs) generated remotely with radiation pressure. Methods: A FEM model was developed to solve the inverse wave propagation problem and obtain viscoelastic properties of interrogated media. The inverse problem was formulated and solved in the frequency domain and its robustness to noise and geometric constraints was evaluated. The proposed model was validated in vitro with two independent rheology methods on several homogeneous and heterogeneous breast tissue-mimicking phantoms over a broad range of frequencies (up to 400 Hz). Results: Viscoelastic properties matched benchmark rheology methods with discrepancies of 8%.38% for the shear modulus G″ and 9%.67% for the loss modulus G″. The robustness study indicated good estimations of storage and loss moduli (maximum mean errors of 19% on G″ and 32% on G″) for signal-to-noise ratios between 19.5 and 8.5 dB. Larger errors were noticed in the case of biases in lesion dimension and position. Conclusions: The ATSW method revealed that it is possible to estimate the viscoelasticity of biological tissues with torsional shear waves when small biases in lesion geometry exist. © 2016 American Association of Physicists in Medicine.


Strandman S.,Rheolution Inc. | Henni A.H.,Rheolution Inc. | Schmitt C.,Rheolution Inc.
NSTI: Advanced Materials - TechConnect Briefs 2015 | Year: 2015

Measuring the viscoelastic properties of soft food materials with precision for industrial QC and production process control is a continuing challenge Research laboratory equipments are typically not adapted for industrial use and arc costly bccausc of required capital investment and high operational costs (only highly skilled professionals can cffccicntlv operate rhcomctcrs) On the other hand, texturometers that are widely used in the industry lack precision and do not allow controlling the production process. Rheolution Inc. has developed new. simple to use and cost-cfTeclive instrument series. ElastoSensTM and CoaguSens™, for real-time quality control and production process control of food products and ingredients The technological principle of these instruments is purely mechanical and its day-to-day use is much simpler than the use of traditional instruments, such as rhcomctcrs. The capabilities of ElastoSens™ will be presented through the results of viscoelastic testing of gelation and melting processes of various ingredients and food products CoaguSensTM, the processing hall version of tlie technology, was used in cheese production plants for at-line mechanical monitoring of milk coagulation processes and cutting time determination on the basis of curd elasticity The results showed reduced variability (-45%) in yield after adopting CoaguSens™ as part of cheesemaking process. This allows refining the process and leads to considerable savings upon improved yield and quality1. Rapid quantitative measurement of curd firmness facilitates farther automation of the cutting step. © 2015 by TechConnect. All rights reserved.


There is provided a system and method for the measurements of viscoelastic properties of a soft sample in which the system incorporates a sample holder that has a membrane with a flexural rigidity that is less than the flexural rigidity of the main body and allowing vibration of the membrane-sample vibration unit in response to a vibration excitation to create resonance vibration modes that are detected to derive the viscoelastic properties.

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