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Papers by maxime lescanne
Journal of Biomedical Optics, 2016
Optical coherence tomography (OCT) can map the stiffness of biological tissue by imaging mechanic... more Optical coherence tomography (OCT) can map the stiffness of biological tissue by imaging mechanical perturbations (shear waves) propagating in the tissue. Most shear wave elastography (SWE) techniques rely on active shear sources to generate controlled displacements that are tracked at ultrafast imaging rates. Here, we propose a noise-correlation approach to retrieve stiffness information from the imaging of diffuse displacement fields using low-frame rate spectral-domain OCT. We demonstrated the method on tissue-mimicking phantoms and validated the results by comparison with classic ultrafast SWE. Then we investigated the in vivo feasibility on the eye of an anesthetized rat by applying noise correlation to naturally occurring displacements. The results suggest a great potential for passive elastography based on the detection of natural pulsatile motions using conventional spectral-domain OCT systems. This would facilitate the transfer of OCT-elastography to clinical practice, in particular, in ophthalmology or dermatology.
The Journal of the Acoustical Society of America, 2016
Ultrasound shear wave elastography is a well established tool for characterization of biologic ti... more Ultrasound shear wave elastography is a well established tool for characterization of biologic tissues. While it has found application in various medical disciplines such as oncology and urology its feasibility for pneumology still has to be shown. We provide experimental results of ultrasound shear wave elastography of porous materials in phantoms and ex-vivo lung tissue. Phantom foams immersed in water show a strong phase velocity dispersion with increasing frequency. Two regimes can be identified in the dispersion curves in the investigated frequency range from 50 to 700 Hz. These experimental results are in reasonable agreement with the theory of porous materials. The results from water-filled phantom foams are compared to gelatin-filled phantom foams. Finally, the phantom study is compared to surface waves dispersion curves of porcine lungs obtained with an ultra-fast optical camera and the first results of ex-vivo shear wave elastography in porcine lung. Ultrasound shear wave elastography is standar...
Physics in Medicine & Biology, 2019
Elastography consists in evaluating the propagation speed of waves into a tissue to estimate its ... more Elastography consists in evaluating the propagation speed of waves into a tissue to estimate its stiffness. Usually this method is based on Ultrasounds, magnetic resonance imaging or optical coherent tomography. This paper proposes a simple optic method using ultrafast cameras. Based on digital image correlation (DIC), the tracking of elastic surface wave from white light intensity pattern, allows estimating the propagation speed as an indicator of the tissue local stiffness. Two configurations are presented: (1) 2D imaging of a flat phantom surface with a single camera and (2) 3D imaging of a curved phantom surface with two cameras. As a feasibility study of the first configuration, surface wave speed was measured on isotropic and anisotropic phantoms. Comparisons with ultrasound methods fully validate this approach. Although more sophisticated, the second configuration account for propagation distortions caused by locally curved topology. Triangulation techniques used to retrieve local topology are named stereo-correlation in the field of biomechanics. Stereo-elastography is thus proposed to determine tissue local elasticity from any soft tissue surface wave.
Journal of Biomedical Optics, 2016
Optical coherence tomography (OCT) can map the stiffness of biological tissue by imaging mechanic... more Optical coherence tomography (OCT) can map the stiffness of biological tissue by imaging mechanical perturbations (shear waves) propagating in the tissue. Most shear wave elastography (SWE) techniques rely on active shear sources to generate controlled displacements that are tracked at ultrafast imaging rates. Here, we propose a noise-correlation approach to retrieve stiffness information from the imaging of diffuse displacement fields using low-frame rate spectral-domain OCT. We demonstrated the method on tissue-mimicking phantoms and validated the results by comparison with classic ultrafast SWE. Then we investigated the in vivo feasibility on the eye of an anesthetized rat by applying noise correlation to naturally occurring displacements. The results suggest a great potential for passive elastography based on the detection of natural pulsatile motions using conventional spectral-domain OCT systems. This would facilitate the transfer of OCT-elastography to clinical practice, in particular, in ophthalmology or dermatology.
The Journal of the Acoustical Society of America, 2016
Ultrasound shear wave elastography is a well established tool for characterization of biologic ti... more Ultrasound shear wave elastography is a well established tool for characterization of biologic tissues. While it has found application in various medical disciplines such as oncology and urology its feasibility for pneumology still has to be shown. We provide experimental results of ultrasound shear wave elastography of porous materials in phantoms and ex-vivo lung tissue. Phantom foams immersed in water show a strong phase velocity dispersion with increasing frequency. Two regimes can be identified in the dispersion curves in the investigated frequency range from 50 to 700 Hz. These experimental results are in reasonable agreement with the theory of porous materials. The results from water-filled phantom foams are compared to gelatin-filled phantom foams. Finally, the phantom study is compared to surface waves dispersion curves of porcine lungs obtained with an ultra-fast optical camera and the first results of ex-vivo shear wave elastography in porcine lung. Ultrasound shear wave elastography is standar...
Physics in Medicine & Biology, 2019
Elastography consists in evaluating the propagation speed of waves into a tissue to estimate its ... more Elastography consists in evaluating the propagation speed of waves into a tissue to estimate its stiffness. Usually this method is based on Ultrasounds, magnetic resonance imaging or optical coherent tomography. This paper proposes a simple optic method using ultrafast cameras. Based on digital image correlation (DIC), the tracking of elastic surface wave from white light intensity pattern, allows estimating the propagation speed as an indicator of the tissue local stiffness. Two configurations are presented: (1) 2D imaging of a flat phantom surface with a single camera and (2) 3D imaging of a curved phantom surface with two cameras. As a feasibility study of the first configuration, surface wave speed was measured on isotropic and anisotropic phantoms. Comparisons with ultrasound methods fully validate this approach. Although more sophisticated, the second configuration account for propagation distortions caused by locally curved topology. Triangulation techniques used to retrieve local topology are named stereo-correlation in the field of biomechanics. Stereo-elastography is thus proposed to determine tissue local elasticity from any soft tissue surface wave.