1. Articles from Guy Lamouche

    1-24 of 35 1 2 »
    1. Comparison of laser triangulation, phase shift triangulation and swept source optical coherence Tomography for nondestructive inspection of objects with micrometric accuracy

      Comparison of laser triangulation, phase shift triangulation and swept source optical coherence Tomography for nondestructive inspection of objects with micrometric accuracy

      We compare the performance of laser triangulation, phase shift triangulation and swept source optical coherence tomography (SSOCT) for quantitative nondestructive inspection. Measurement accuracies of these three optical 3D imaging techniques can be reduced to a few tens of micrometers or less, making it possible to locate and geometrically characterize defects at the micrometric scale. We consider surfaces with different optical properties and we discuss the ability of these techniques to reconstruct the surface profiles. For opaque surfaces, the three techniques provide very similar results. For semi-transparent and transparent surfaces, the accuracy achieved by SSOCT relies on the capability of detecting ...

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    2. Postdoctoral Position in Triangulated Optical Coherence Tomography at National Research Council Canada

      Postdoctoral Position in Triangulated Optical Coherence Tomography at National Research Council Canada

      Location : Ottawa, ON and Boucherville, QC Optical coherence tomography (OCT) is an imaging technique that captures volumetric images of a scattering medium. Because of its interferometric nature, it is robust to local variations of light intensities and only requires a direct line of sight. Triangulation-based 3D imaging (laser scanning or structured-light systems), on the other hand, can perform fast surface measurements on large working volumes but requires two lines of sight. A hybrid technology would allow fast acquisition speed, large coverage, and capability of inspecting hard-to-reach surfaces. We thus seek a postdoctoral fellow (PDF) to lead the development of this ...

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    3. External amplification of OCT swept-sources for challenging applications: from 10 mW to more than 120 mW

      External amplification of OCT swept-sources for challenging applications: from 10 mW to more than 120 mW

      For bioimaging applications, commercial swept-sources currently provide enough power (tens of milliwatts) insuring good imaging condition without damaging the tissues. For industrial applications, more power is needed since the amount of light collected can be very low due to challenging measurement conditions or due to poor sample reflectivity. To address this challenge, we explore three different setups to externally amplify the output of a commercial swept-source: a booster semiconductor optical amplifier (BOA), an erbium-doped fiber amplifier (EDFA) and a combination of both. These external amplification setups allow the exploration of emerging OCT applications without the need to develop new hardware.

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    4. Processing to determine optical parameters of atherosclerotic disease from phantom and clinical intravascular optical coherence tomography three-dimensional pullbacks

      Processing to determine optical parameters of atherosclerotic disease from phantom and clinical intravascular optical coherence tomography three-dimensional pullbacks

      Analysis of intravascular optical coherence tomography (IVOCT) data has potential for real-time in vivo plaque classification. We developed a processing pipeline on a three-dimensional local region of support for estimation of optical properties of atherosclerotic plaques from coronary artery, IVOCT pullbacks. Using realistic coronary artery disease phantoms, we determined insignificant differences in mean and standard deviation estimates between our pullback analyses and more conventional processing of stationary acquisitions with frame averaging. There was no effect of tissue depth or oblique imaging on pullback parameter estimates. The method’s performance was assessed in comparison with observer-defined standards using clinical pullback data ...

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    5. Artery phantoms for intravascular optical coherence tomography: diseased arteries

      Artery phantoms for intravascular optical coherence tomography: diseased arteries

      We propose and test various strategies for the creation of artery phantoms mimicking different kinds of diseased arteries when imaged by intravascular optical coherence tomography (IVOCT). We first review the method for making healthy artery phantoms. We then describe the procedure to fabricate diseased artery phantoms with intima thickening, lipid pool, thin-capped fibroatheroma, calcification, and restenosis (homogeneous and layered) after stent apposition. For each case, a phantom is fabricated, an IVOCT image is obtained, and the image is compared to that of a real artery.

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    6. Intravascular optical coherence tomography to characterize tissue deformation during angioplasty: preliminary experiments with artery phantoms

      Intravascular optical coherence tomography to characterize tissue deformation during angioplasty: preliminary experiments with artery phantoms

      We explored the potential of intravascular optical coherence tomography (IVOCT) to assess deformation during angioplasty balloon inflation. Using a semi-compliant balloon and artery phantoms, we considered two experimental scenarios. The goal for the first scenario was to investigate if variation in the elasticity of the structure surrounding the balloon could be sensed by IVOCT monitoring. In this scenario, we used three single-layer phantoms with various mechanical properties. Image analysis was performed to extract the inner and outer diameters of the phantoms at various pressures. The goal for the second scenario was twofold. First, we investigated the IVOCT capability to monitor ...

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    7. Invitation to Join and Participate in a Optical Coherence Tomography Phantoms Initiative Forum

      Invitation to Join and Participate in a Optical Coherence Tomography Phantoms Initiative Forum

      Anant Agrawal from the US Food and Drug Administration, Brendan Kennedy from the University of Western Australia, Guy Lamouche of the National Research Council Canada, and Pete Tomlins from Queen Mary, University of London invite your participation in the Optical Coherence Tomography Phantoms Initiative Forum. To sign up or to find out more details please click this LINK.

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    8. Review of tissue simulating phantoms with controllable optical, mechanical and structural properties for use in optical coherence tomography

      Review of tissue simulating phantoms with controllable optical, mechanical and structural properties for use in optical coherence tomography

      We review the development of phantoms for optical coherence tomography (OCT) designed to replicate the optical, mechanical and structural properties of a range of tissues. Such phantoms are a key requirement for the continued development of OCT techniques and applications. We focus on phantoms based on silicone, fibrin and poly(vinyl alcohol) cryogels (PVA-C), as we believe these materials hold the most promise for durable and accurate replication of tissue properties.

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    9. Optimal signal processing of nonlinearity in swept-source and spectral-domain optical coherence tomography

      Optimal signal processing of nonlinearity in swept-source and spectral-domain optical coherence tomography

      We demonstrate the efficiency of the convolution using an optimized Kaiser–Bessel window to resample nonlinear data in wavenumber for Fourier-domain optical coherence tomography (OCT). We extend our previous experimental demonstration that was performed with a specific swept-source nonlinearity. The method is now applied to swept-source OCT data obtained for various simulated swept-source nonlinearities as well as spectral-domain OCT data obtained from both simulations and experiments. Results show that the new optimized method is the most efficient for handling all the different types of nonlinearities in the wavenumber domain that one can encounter in normal practice. The efficiency of the ...

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    10. Real-time Control of Angioplasty Balloon Inflation Based on Feedback from Intravascular Optical Coherence Tomography: Experimental Validation on an Excised Heart and a Beating Heart Model

      Real-time Control of Angioplasty Balloon Inflation Based on Feedback from Intravascular Optical Coherence Tomography: Experimental Validation on an Excised Heart and a Beating Heart Model

      We report on real-time control of balloon inflation inside porcine arteries. In a first step, experiments were done in a coronary artery of an excised heart. In a second step, experiments were done in a beating heart setup providing conditions very close to in vivo conditions without the complications. A programmable syringe pump was used to inflate a compliant balloon in arteries, while intravascular optical coherence tomography (IVOCT) monitoring was performed. In a feedback loop, IVOCT images were processed to provide the balloon diameter values in real-time to control the pump action in order to achieve a target diameter. In ...

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    11. Consensus Standards for Acquisition, Measurement, and Reporting of Intravascular Optical Coherence Tomography Studies: A Report From the International Working Group for Intravascular Optical Coherence Tomography Standardization and Validation

      Consensus Standards for Acquisition, Measurement, and Reporting of Intravascular Optical Coherence Tomography Studies: A Report From the International Working Group for Intravascular Optical Coherence Tomography Standardization and Validation

      Objectives: The purpose of this document is to make the output of the International Working Group for Intravascular Optical Coherence Tomography (IWG-IVOCT) Standardization and Validation available to medical and scientific communities, through a peer-reviewed publication, in the interest of improving the diagnosis and treatment of patients with atherosclerosis, including coronary artery disease.Background: Intravascular optical coherence tomography (IVOCT) is a catheter-based modality that acquires images at a resolution of 10 μm, enabling visualization of blood vessel wall microstructure in vivo at an unprecedented level of detail. IVOCT devices are now commercially available worldwide, there is an active user base, and ...

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    12. OCT Phantoms Initiative: A new effort to bring standardized tools for OCT system characterization and validation to the community

      OCT Phantoms Initiative: A new effort to bring standardized tools for OCT system characterization and validation to the community
      Over the past two decades, the capabilities, applications, and usage of OCT have advanced remarkably. Given the maturity of OCT, there is an imminent need for widely available and standardized tools to benchmark OCT device performance. Controlled test objects, generally known as phantoms, are essential to satisfy this need by serving as a stable, well-characterized reference which is periodically imaged. The proper phantom can ensure data accuracy and consistency over time, among multiple instruments, and across device manufacturers. This is a key step towards standardization and quality assurance on par with the most established medical imaging modalities. The OCT Phantoms ...
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    13. Real-time Control of Angioplasty Balloon Inflation Based on Feedback from Intravascular Optical Coherence Tomography: Preliminary Study on an Artery Phantom

      Real-time Control of Angioplasty Balloon Inflation Based on Feedback from Intravascular Optical Coherence Tomography: Preliminary Study on an Artery Phantom

      A method is proposed to achieve computerized control of angioplasty balloon inflation, based on feedback from intravascular optical coherence tomography (IVOCT). Controlled balloon inflation could benefit clinical applications, cardiovascular research, and medical device industry. The proposed method was experimentally tested for balloon inflation within an artery phantom. During balloon inflation, luminal contour of the phantom was extracted from IVOCT images in real-time. Luminal diameter was estimated from the obtained contour and was used in a feedback loop. Based on the estimated actual diameter and a target diameter, a computer controlled a programmable syringe pump to deliver or withdraw liquid in ...

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    14. Artery phantoms for intravascular optical coherence tomography: healthy arteries

      Artery phantoms for intravascular optical coherence tomography: healthy arteries
      We present a method to make phantoms of coronary arteries for intravascular optical coherence tomography (IV-OCT). The phantoms provide a calibrated OCT response similar to the layered structure of arteries. The optical properties of each layer are achieved with specific concentrations of alumina and carbon black in a silicone matrix. This composition insures high durability and also approximates the elastic properties of arteries. The phantoms are fabricated in a tubular shape by the successive deposition and curing of liquid silicone mixtures on a lathe setup.
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    15. Optical coherence tomography layer thickness characterization of a mock artery during angioplasty balloon deployment

      Optical coherence tomography layer thickness characterization of a mock artery during angioplasty balloon deployment

      Optical coherence tomography (OCT) is used to study the deformation of a mock artery in an angioplasty simulation setup. An OCT probe integrated in a balloon catheter provides intraluminal real-time images during balloon inflation. Swept-source OCT is used for imaging. A 4 mm semi-compliant polyurethane balloon is used for experiments. The balloon is inflated inside a custom-built multi-layer artery phantom. The phantom has three layers to mock artery layers, namely, intima, media and adventitia. Semi-automatic segmentation of phantom layers is performed to provide a detailed assessment of the phantom deformation at various inflation pressures. Characterization of luminal diameter and thickness ...

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    16. Detection of inflating balloon in optical coherence tomography images of a porcine artery in a beating heart experiment

      Detection of inflating balloon in optical coherence tomography images of a porcine artery in a beating heart experiment

      Suboptimal results of angioplasty procedures have been correlated to arterial damage during balloon inflation. We propose to monitor balloon inflation during the angioplasty procedure by detecting the balloon contours with intravascular optical coherence tomography (IVOCT). This will shed more light on the interaction between the balloon and the artery and to assess the artery's mechanical response. An automatic edge detection algorithm is applied for detection of the outer surface of an inflating balloon in a porcine artery in a beating heart experiment. A compliant balloon is inflated to deform the artery. IVOCT monitoring of balloon inflation is performed at ...

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    17. Toward better treatment of clogged arteries

      Toward better treatment of clogged arteries
      Real-time detailed monitoring of angioplasty balloon deformation may lead to improved medical devices to treat hardened artery walls. Intravascular optical coherence tomography (IVOCT) is a catheter-based technique that provides detailed cross-sectional imaging of the artery wall with a resolution of the order of ten micrometers. The clinical relevance of IVOCT has been demonstrated in many studies for the diagnosis and treatment monitoring of atherosclerosis1 (hardening and/or thickening of arteries by deposited plaques of cholesterol and other lipids, inflammatory cells, and calcium deposits). The technology is mature enough to be distributed commercially.2 Images may be acquired during a ‘pullback ...
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    18. Tailoring wavelength sweep for SS-OCT with a programmable picosecond laser

      Tailoring wavelength sweep for SS-OCT with a programmable picosecond laser

      This paper presents a unique and novel picosecond laser source that offers complete tailoring of the wavelength sweep and that benefits swept-source optical coherence tomography (SS-OCT) applications. Along with the advantages of a fiber-based architecture, the source is a fully programmable, electronically controlled actively mode-locked laser capable of rapidly tuning the wavelength and pulse characteristics. Furthermore, several sweep modes and configurations are available which can be defined by range, with linear sweeps in wavelength or k-space, or by arbitrary wavelengths. The source design is discussed and its use in SS-OCT with a prototype using a semiconductor optical amplifier as a ...

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    19. Optical Coherence Tomography Characterization of Balloon Diameter and Wall Thickness

      Optical Coherence Tomography Characterization of Balloon Diameter and Wall Thickness
      (An intravascular optical coherence tomography probe is integrated in a computerized angioplasty balloon deployment system. The resulting setup can be useful in many applications. In this paper, based on the acquired intraluminal images, we achieve a detailed assessment of the diameter and wall thickness of the inflated balloon at different pressures. Such analysis is helpful in testing the balloon quality, in assessing deformation model, or in validating new balloon designs.
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    20. Intravascular optical coherence tomography on a beating heart model

      Intravascular optical coherence tomography on a beating heart model
      The advantages and limitations of using a beating heart model in the development of intravascular optical coherence tomography are discussed. The model fills the gap between bench experiments, performed on phantoms and excised arteries, and whole animal in-vivo preparations. The beating heart model is stable for many hours, allowing for extended measurement times and multiple imaging sessions under in-vivo conditions without the complications of maintaining whole-animal preparation. The perfusate supplying the heart with nutrients can be switched between light scattering blood to a nonscattering perfusate to allow the optical system to be optimized without the need of an efficient blood ...
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    21. Optical coherence tomography monitoring of angioplasty balloon inflation in a deployment tester

      Optical coherence tomography monitoring of angioplasty balloon inflation in a deployment tester
      Hamed Azarnoush, Sebastien Vergnole, Rafik Bourezak, Benoit Boulet, and Guy Lamouche We present an innovative integration of an intravascular optical coherence tomography probe into a computerized balloon deployment system to monitor the balloon inflation process. The high-resolution intraluminal imaging of the balloon provides a detailed assessment of the balloon quality and, conse ... [Rev. Sci. Instrum. 81, 083101 (2010)] published Mon Aug 2, 2010.
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    22. Experimental validation of an optimized signal processing method to handle non-linearity in swept-source optical coherence tomography

      Experimental validation of an optimized signal processing method to handle non-linearity in swept-source optical coherence tomography
      We evaluate various signal processing methods to handle the non-linearity in wavenumber space exhibited by most laser sources for swept-source optical coherence tomography. The following methods are compared for the same set of experimental data: non-uniform discrete Fourier transforms with Vandermonde matrix or with Lomb periodogram, resampling with linear interpolation or spline interpolation prior to fast-Fourier transform (FFT), and resampling with convolution prior to FFT. By selecting an optimized Kaiser-Bessel window to perform the convolution, we show that convolution followed by FFT is the most efficient method. It allows small fractional oversampling factor between 1 and 2, thus a minimal ...
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    23. Automatic lumen segmentation from intravascular OCT images

      Automatic lumen segmentation from intravascular OCT images
      In the last decade intravascular optical coherence tomography has known a tremendous progress. Its high resolution (5- 10µm) allows coronary plaque characterization, vulnerable plaque assessment, and the guidance of intravascular interventions. However, one intravascular OCT sequence contains hundreds of frames, and their interpretation requires a lot of time and energy. Therefore, there is a strong need for automated segmentation algorithms to process this large amount of data. In this article, we present an automated algorithm to extract lumen contours from images obtained with intravascular Optical Coherence Tomography (OCT). Unlike existing methods, our algorithm requires no post- or preprocessing of the ...
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    24. Multilayer tubular phantoms for optical coherence tomography

      Multilayer tubular phantoms for optical coherence tomography
      We report preliminary results toward making artery phantoms for Optical Coherence Tomography (OCT) that also exhibit mechanical properties similar to arteries for large deformation regimes. A matrix of PVA cryogels is used to obtain the strain hardening effect characteristic of arteries. Means of adjusting the optical properties of PVA cryogels are investigated and the resulting mechanical properties are characterized.
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    1-24 of 35 1 2 »
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    1. (35 articles) Guy Lamouche
    2. (34 articles) National Research Council Canada
    3. (16 articles) Sebastien Vergnole
    4. (11 articles) Charles-Étienne Bisaillon
    5. (8 articles) Marc L. Dufour
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    Automatic lumen segmentation from intravascular OCT images Experimental validation of an optimized signal processing method to handle non-linearity in swept-source optical coherence tomography Tailoring wavelength sweep for SS-OCT with a programmable picosecond laser OCT Phantoms Initiative: A new effort to bring standardized tools for OCT system characterization and validation to the community Consensus Standards for Acquisition, Measurement, and Reporting of Intravascular Optical Coherence Tomography Studies: A Report From the International Working Group for Intravascular Optical Coherence Tomography Standardization and Validation Invitation to Join and Participate in a Optical Coherence Tomography Phantoms Initiative Forum Postdoctoral Position in Triangulated Optical Coherence Tomography at National Research Council Canada Optical coherence tomography angiography of foveal neovascularisation in proliferative diabetic retinopathy Treating port wine stain birthmarks using dynamic optical coherence tomography-guided setting Repeatability of quantitative measurements of retinal layers with SD-OCT and agreement between vertical and horizontal scan protocols in healthy eyes Perimeter Medical Imaging Closes Oversubscribed $C4.4M Financing Time-domain optical coherence tomography system based on moving-optical-wedge interferometer