Dr. Amir Nahas Profile

Dr. Amir Nahas

Assistant Professor at CNRS ICUBE

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Author

Publications (16)

Proceedings Article | 13 March 2024 Presentation

Shear wave elastography with single-shot off-axis FF-OCT (SO-FF-OCT) approach

Emmanuel Martins Seromenho, Nina Dufour, Maud Legrand, Jesse Schiffler, Sybille Facca, Nadia Bahlouli, Amir Nahas

Proceedings Volume PC12844, PC128440S (2024) https://doi.org/10.1117/12.3002947

KEYWORDS: Elastography, Optical coherence tomography, Biomedical applications, Biological imaging, Wave propagation, Ultrasonography, Tissues, Scattering, Reflection, Phase distribution

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Proceedings Article | 13 March 2024 Presentation

Noise correlation elastography using digital holography in mechanically anisotropic media

Nina Dufour, Agathe Marmin, Emmanuel Martins Seromenho, Maud Legrand, Simon Chatelin, Amir Nahas

Proceedings Volume PC12844, PC128440Q (2024) https://doi.org/10.1117/12.3002358

KEYWORDS: Elastography, Digital holography, Tissues, Imaging systems, Biological samples, Ultrasonography, Optical imaging, Optical coherence tomography, Magnetic resonance imaging, Anisotropy

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Proceedings Article | 13 March 2024 Presentation

Single-shot off-axis FF-OCT (SO-FF-OCT) imaging: in-vivo optical tomography and Doppler imaging

Emmanuel Martins Seromenho, Nina Dufour, Jesse Schiffler, Vincent Maioli, Sybille Facca, Nadia Bahlouli, Amir Nahas

Proceedings Volume PC12830, PC1283021 (2024) https://doi.org/10.1117/12.3002928

KEYWORDS: In vivo imaging, Biological imaging, Doppler tomography, Biomedical optics, Optical imaging, Optical tomography, Biological samples, Tissues, Scattering, Phase shifts

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Proceedings Article | 13 March 2024 Poster

Machine learning based full field noise correlation elastography

Maud Legrand, Nina Dufour, Emmanuel Martins Seromenho, Nadia Bahlouli, Amir Nahas

Proceedings Volume PC12844, PC128440V (2024) https://doi.org/10.1117/12.2691086

KEYWORDS: Elastography, Machine learning, Deep learning, Correlation function, Image processing, Viscosity, Viscoelasticity, Tissues, Tissue optics, Simulations

Proceedings Article | 13 March 2024 Poster

Noise correlation elastography for full field optical imaging systems

Nina Dufour, Maud Legrand, Emmanuel Martins Seromenho, Paul Montgomery, Amir Nahas

Proceedings Volume PC12844, PC128440W (2024) https://doi.org/10.1117/12.3002345

KEYWORDS: Elastography, Video, Endoscopes, Endoscopy, Tumors, Colorectal cancer, Ultrasonography, Optical coherence, Magnetic resonance imaging, Light sources and illumination

Proceedings Article | 9 March 2023 Presentation

In-vivo multimodal single-shot off-axis FF-OCT (SO-FF-OCT) imaging: optical tomography and shear wave elastography

Emmanuel Martins Seromenho, Agathe Marmin, Sybille Facca, Nadia Bahlouli, Amir Nahas

Proceedings Volume PC12367, PC1236718 (2023) https://doi.org/10.1117/12.2652601

KEYWORDS: Elastography, In vivo imaging, Optical tomography, Optical imaging, Tissues, Phase shifts, Optical coherence tomography, Biomedical optics, Ultrasonography, Tomography

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Proceedings Article | 3 December 2021 Paper

Digital holography-based quantitative elastography using noise-correlation

Agathe Marmin, Simon Chatelin, Manuel Flury, Sybille Facca, Stefan Catheline, Amir Nahas

Proceedings Volume 11921, 1192108 (2021) https://doi.org/10.1117/12.2615455

KEYWORDS: Digital holography, Elastography, Tissues, Point spread functions, Optical coherence tomography, Holography, Polymers, Anisotropy, Actuators, Tissue optics

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SPIE Journal Paper | 19 August 2021 Open Access

Time-of-flight and noise-correlation-inspired algorithms for full-field shear-wave elastography using digital holography

Agathe Marmin, Gabrielle Laloy-Borgna, Sybille Facca, Sylvain Gioux, Stefan Catheline, Amir Nahas

JBO, Vol. 26, Issue 08, 086006, (August 2021) https://doi.org/10.1117/12.10.1117/1.JBO.26.8.086006

KEYWORDS: Elastography, Wave propagation, Tissues, Digital holography, Algorithm development, Video, Computer simulations, Speckle, Signal to noise ratio, Correlation function

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Significance: Quantitative stiffness information can be a powerful aid for tumor or fibrosis diagnosis. Currently, very promising elastography approaches developed for non-contact biomedical imaging are based on transient shear-waves imaging. Transient elastography offers quantitative stiffness information by tracking the propagation of a wave front. The most common method used to compute stiffness from the acquired propagation movie is based on shear-wave time-of-flight calculations. Aim: We introduce an approach to transient shear-wave elastography with spatially coherent sources, able to yield full-field quantitative stiffness maps with reduced artifacts compared to typical artifacts observed in time-of-flight. Approach: A noise-correlation algorithm developed for passive elastography is adapted to spatially coherent narrow or any band sources. This noise-correlation-inspired (NCi) method is employed in parallel with a classic time-of-flight approach. Testing is done on simulation images, experimental validation is conducted with a digital holography setup on controlled homogeneous samples, and full-field quantitative stiffness maps are presented for heterogeneous samples and ex-vivo biological tissues. Results: The NCi approach is first validated on simulations images. Stiffness images processed by the NCi approach on simulated inclusions display significantly less artifacts than with a time-of-flight reconstruction. The adaptability of the NCi algorithm to narrow or any band shear-wave sources was tested successfully. Experimental testing on homogeneous samples demonstrates similar values for both the time-of-flight and the NCi approach. Soft inclusions in agarose sample could be resolved using the NCi method and feasibility on ex-vivo biological tissues is presented. Conclusions: The presented NCi approach was successful in computing quantitative full-field stiffness maps with narrow and broadband source signals on simulation and experimental images from a digital holography setup. Results in heterogeneous media show that the NCi approach could provide stiffness maps with less artifacts than with time-of-flight, demonstrating that a NCi algorithm is a promising approach for shear-wave transient elastography with spatially coherent sources.

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Proceedings Article | 5 March 2021 Poster + Presentation

Noise-correlation-based elastography using digital holography in anisotropic media

Agathe Marmin, Simon Chatelin, Stefan Catheline, Amir Nahas

Proceedings Volume 11645, 116451E (2021) https://doi.org/10.1117/12.2578645

KEYWORDS: Elastography, Digital holography, Tissues, Optical coherence tomography, Wave propagation, Polymers, Optical properties, Optical imaging, Mach-Zehnder interferometers, Imaging systems

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Proceedings Article | 5 March 2021 Presentation

Time-reversal-based passive elastography using full-field digital holography

Agathe Marmin, Stefan Catheline, Amir Nahas

Proceedings Volume 11645, 116450D (2021) https://doi.org/10.1117/12.2578560

KEYWORDS: Elastography, Digital holography, Tissues, Optical coherence tomography, Ultrasonography, Phase measurement, Magnetic resonance imaging, Tissue optics, Optical resolution, In vivo imaging

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Proceedings Article | 5 March 2021 Presentation

Quantitative full-field transient elastography based on digital holography

Agathe Marmin, Gabrielle Laloy-Borgna, Sybille Facca, Sylvain Gioux, Stefan Catheline, Amir Nahas

Proceedings Volume 11645, 116450A (2021) https://doi.org/10.1117/12.2578581

KEYWORDS: Elastography, Digital holography, Wave propagation, Ultrasonography, Tissues, Optical coherence tomography, Natural surfaces, Mach-Zehnder interferometers, Cameras

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SPIE Journal Paper | 13 March 2019 Open Access

Real-time, wide-field, and quantitative oxygenation imaging using spatiotemporal modulation of light

Manon Schmidt, Enagnon Aguénounon, Amir Nahas, Murielle Torregrossa, Bruce Tromberg, Wilfried Uhring, Sylvain Gioux

JBO, Vol. 24, Issue 07, 071610, (March 2019) https://doi.org/10.1117/12.10.1117/1.JBO.24.7.071610

KEYWORDS: Modulation, Optical properties, Cameras, Image processing, Absorption, Diffuse optical imaging, Scattering, Light scattering, Blood, Tissues

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Proceedings Article | 24 May 2018 Presentation

Real-time oxygenation imaging using spatio-temporal modulation of light (Conference Presentation)

Manon Schmidt, Amir Nahas, Swapnesh Panigrahi, Murielle Torregrossa, Sylvain Gioux

Proceedings Volume 10685, 1068516 (2018) https://doi.org/10.1117/12.2306469

KEYWORDS: Modulation, Optical properties, Real time imaging, Surgery, Tissues, Tissue optics, Diffuse optical imaging, Absorption, Scattering, Image processing

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Most surgeries are currently performed subjectively, with outcomes that are largely dependent on the experience of the surgeon. Providing objective information about tissue that need to be resected or avoided could reduce the variability in surgical outcomes. Spatial Frequency Domain Imaging (SFDI) is a novel diffuse optical imaging method that has the potential to identify tissue viability over a large field of view. In this method, a spatial sinusoidal pattern is projected onto the tissue to get the optical properties of the tissue at each pixel. More recently, Single Snapshot of Optical Properties (SSOP) hase been developed to provide such image feedback in real-time within the specific constraints of surgery. However, while SSOP has been shown to provide information about tissues at a single wavelength in real-time, during surgical applications, it is critical to obtain spectrally-resolved functional information that can be easily interpreted by the surgeons. Optical properties at multiple wavelengths are therefore needed to correlate the absorption and scattering coefficients with the tissue functional and structural information. In this work, we propose a novel method relying on spatio-temporal modulation of light to obtain multispectral optical properties in real time. A temporal-encoding method is used to distinguish different wavelengths by modulating each wavelength at a one particular chosen frequency. The temporally-modulated light is then used to project sinusoidal patterns onto the tissues for SSOP processing. The scene is then recorded with a fast camera to get multiple information in 3 dimensions: two spatial dimensions for SSOP and the third temporal dimension for wavelength. Discrete Fourier Transform (DFT) is used to separate the modulation frequencies pixels by pixels, and each 2D image obtained for every wavelength is processed using SSOP to obtain absorption and scattering coefficients. Finally, the optical properties at each wavelength are used to provide functional and structural information about tissues. We validated this proof of concept using 2 wavelengths (665 and 860nm) during phantom measurements and in vivo by obtaining real-time oxygenation videos. This work lays the foundation for the clinical translation of real-time quantitative multispectral imaging.

SPIE Journal Paper | 23 December 2016 Open Access

High-speed phase-shifting common-path quantitative phase imaging with a piezoelectric actuator

Séverine Coquoz, Amir Nahas, Miguel Sison, Antonio Lopez, Theo Lasser

JBO, Vol. 21, Issue 12, 126019, (December 2016) https://doi.org/10.1117/12.10.1117/1.JBO.21.12.126019

KEYWORDS: Mirrors, Phase shifts, Phase imaging, Actuators, Video, Phase shift keying, Cameras, Microscopy, Microscopes, Phase shifting

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Proceedings Article | 26 April 2016 Presentation

Three dimensional time lapse imaging of live cell mitochondria with photothermal optical lock-in optical coherence microscopy (Conference Presentation)

Miguel Sison, Sabyasachi Chakrabortty, Jerome Extermann, Amir Nahas, Christophe Pache, Tanja Weil, Theo Lasser

Proceedings Volume 9697, 96971Y (2016) https://doi.org/10.1117/12.2214761

KEYWORDS: 3D image processing, Live cell imaging, Optical coherence microscopy, Nanoparticles, Coherence (optics), Microscopes, Gold, Luminescence, Confocal microscopy, Optical coherence tomography

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SPIE Journal Paper | 19 December 2013 Open Access

From supersonic shear wave imaging to full-field optical coherence shear wave elastography

Amir Nahas, Mickael Tanter, Thu-Mai Nguyen, Jean-Marie Chassot, Mathias Fink, A. Claude Boccara

JBO, Vol. 18, Issue 12, 121514, (December 2013) https://doi.org/10.1117/12.10.1117/1.JBO.18.12.121514

KEYWORDS: Elastography, Ultrasonography, Wave propagation, Ultrasonics, Optical coherence tomography, Tissues, Coherence (optics), Optical imaging, Cameras, Biomedical optics

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