Over the past few decades, a multitude of optical imaging techniques have emerged. Among them, full-field optical coherence tomography (FF-OCT) has gained significant importance in various biomedical applications. Indeed, FF-OCT stands out as a noninvasive and label-free imaging method capable of generating high-resolution 3D microscopic images of light-scattering biological specimens. However, FF-OCT approach is limited for in-vivo imaging and images from FF-OCT lack the specificity required for accurate diagnosis. Hence, there is a need to have access to in-vivo imaging and to incorporate additional contrast modalities, such as elastography, into the FF-OCT technique. Indeed, the combination of FF-OCT with shear wave elastography enables the quantitative assessment of tissue stiffness at a resolution of a few micrometers. In this context, we present a novel FF-OCT approach that enables single-shot acquisitions, making it well-suited for both in-vivo imaging and transient shear wave elastography.
The last few decades have seen the emergence of a huge number of optical imaging techniques. Among them, full-field optical coherence tomography (FF-OCT) has become valuable for many biomedical applications. Indeed, FF-OCT is a noninvasive and label-free imaging technique that produces high-resolution 3D microscopic images of scattering biological samples. However, FF-OCT images alone lack of specificity for accurate diagnosis. That is why it is necessary to add new contrast modalities to FF-OCT technique such as elastography. Indeed, coupling FF-OCT with shear wave elastography allows quantitative estimation of the stiffness at a resolution of a few micrometers. We present here our first results on coupling single-shot off-axis FF-OCT (SO-FF-OCT) method with transient shear wave elastography method.
The last few decades have seen the emergence of a huge number of optical imaging techniques. Among them, full-field optical coherence tomography (FF-OCT) has become valuable for many biomedical applications. Indeed, FF-OCT is a noninvasive and label-free imaging technique that produces high-resolution 3D microscopic images of scattering biological samples. Using FF-OCT approach for in-vivo imaging would enable the observation of cell-scale structures in living samples. Moreover, living samples have an active vascularization that can therefore be observed using Doppler imaging. We propose in this study a new FF-OCT approach that enables single-shot acquisitions which is suitable for in-vivo and Doppler imaging.
Full-field optical coherence tomography (FF-OCT) enables high-resolution 3D imaging. FF-OCT is a noninvasive and label-free imaging technique that produces high-resolution microscopy images of scattering biological samples. During the last decade, FF-OCT has become invaluable for many biomedical applications. It requires the extraction of the amplitude and phase components from the interference signal, for which a phase-shifting algorithm is usually used. However, this algorithm is not well adapted for real-time observation of in-vivo samples, therefore limiting the use of FF-OCT for ¬in-vivo imaging and clinical transfer. We propose in this study a new approach in FF-OCT that enables single-shot acquisitions using off-axis digital holography principle with low spatially and temporally coherent source.
Quantitative elastography is performed using noise-correlation on full-field images acquired using digital holography. Experimental results in isotropic and anisotropic polymer samples are presented as well as stiffness images on biological tissues.
KEYWORDS: Elastography, Wave propagation, Tissues, Digital holography, Algorithm development, Video, Computer simulations, Speckle, Signal to noise ratio, Correlation function
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.
Shear-wave elastography is based on the imaging of displacements induced by the propagation of shear-waves through a medium. A full-field off-axis digital holography setup is utilized here to image surface displacements with high sensitivity. A low frame-rate camera is combined with a stroboscopic approach to achieve propagation imaging. We present the latest results using time of flight and time-reversal-based methods to map stiffness from a propagation movie. The methods are tested on simulation images obtained using a finite difference algorithm. Experimental images with the optical setup on agarose test samples mimicking biological tissues and first results on an ex-vivo biological sample are presented.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.