Non-melanoma skin cancer is the most common cancer. On cosmetically sensitive areas, Mohs micrographic surgery is the standard of care; intra-operative margin assessment minimizes the surgical defect while helping to reduce the recurrence rate by a factor of 3 compared to surgical excision. The current Mohs technique relies on frozen section tissue slide preparation, which significantly lengthens operative time and requires on-site trained histotechnicians. Full-field micro-tomography is a novel optical imaging technique based on interferometry. It allows the extraction of a full-field optical coherence tomography (FFOCT) image, representative of the morphology of the tissue, and the dynamic cell information, representative of the intra-cellular metabolic activity. Both images are calculated at the micron-level in a few minutes and without tissue preparation. This multi-centric study aimed to evaluate these combined new imaging modalities for the analysis of skin cancer margins during Mohs surgery.
Over 200 Mohs specimens were imaged in Drexel University College of Medicine, USA, and GHR Mulhouse Sud Alsace, France. An atlas was established of FFOCT images and corresponding histological slides to reveal FFOCT reading criteria of normal and cancerous structures. Dynamic cell information enhanced visualization of cancerous cells and surrounding immune cells, and yielded metabolic quantification of cancerous area versus benign areas. Finally, deep learning algorithms were developed for preliminary results for the automatic detection of cancerous tissue.
Hybrid morphologic and metabolic micro-tomography techniques hold great potential for skin cancer margin assessment. They can potentially reduce recurrence rates and surgery times, optimize clinical workflow, and decrease healthcare costs.
Full Field OCT (FFOCT) is a shot noise limited interferometric microscopy technique that uses incoherent light and has proved to be an effective diagnostic tool in terms of sensitivity and specificity. We have used the FFOCT setup built by LLTech for the analysis of various cancerous tissues corresponding to the following organs: breast, skin, prostate, lungs, ENT, bladder, brain etc. The scores obtained were found in the range between 80 and 98%. To do better and to provide informations that the histology does not carry we have studied, using the same setup, the temporal dependence of our signals which we found to be related to the cellular metabolism. We have used the new high speed and high full well capacity of the Adimec camera to achieve a time analysis ranging between 2 and a few thousands of ms. We thus obtain a new contrast which constitutes a biomarker at the sub-cellular scale. We monitor the characteristic frequencies and amplitude of the signal and display them on the images of the tissues using a new processing code of the time series. This metabolic contrast also reveal the evolution of the activity of cancer cells under treatments such as chemotherapy. We will illustrate this new approach through examples of cancer tissues that are planned to be used as intraoperative tools.
Transthoracic core-needle biopsy under imaging guidance is a common procedure in lung cancer diagnosis. It is performed in order to extract material for histology from a nodule that has previously been detected with radiography or computed tomography in the patient’s chest.
In order to avoid recalling for non-diagnostic material, the radiologists are used to performing several biopsies so that the chance of resection of relevant material is increased. The use of a real-time tool for lung biopsy assessment during biopsy procedure would be valuable to decrease the number of biopsies thus decreasing the risk of complications.
As an answer to this need, LLTech develops an optical imaging device for real time biopsy assessment at cellular level. Based on full-field optical coherence tomography, the system performs micron resolution optical virtual slices in the sample depth within a few minutes. In addition, benefiting from its high-speed acquisition capability, the system quickly records the evolution of this optical slice over time, thus highlighting intracellular residual movements of freshly excised tissue. Both the tissue architecture and the intracellular activity are imaged and combined in an exhaustive analysis that favors the pathologists reading.
LLTech presents the images obtained on dozens of lung biopsies in collaboration with Cochin Hospital radiology and pathology departments to evaluate the potential of dynamic cell imaging on lung cancer assessment.
Despite obvious improvements in visualization of the in vivo cornea through the faster imaging speeds and higher axial resolutions, cellular imaging stays unresolvable task for OCT, as en face viewing with a high lateral resolution is required. The latter is possible with FFOCT, a method that relies on a camera, moderate numerical aperture (NA) objectives and an incoherent light source to provide en face images with a micrometer-level resolution. Recently, we for the first time demonstrated the ability of FFOCT to capture images from the in vivo human cornea1. In the current paper we present an extensive study of appearance of healthy in vivo human corneas under FFOCT examination. En face corneal images with a micrometer-level resolution were obtained from the three healthy subjects. For each subject it was possible to acquire images through the entire corneal depth and visualize the epithelium structures, Bowman’s layer, sub-basal nerve plexus (SNP) fibers, anterior, middle and posterior stroma, endothelial cells with nuclei. Dimensions and densities of the structures visible with FFOCT, are in agreement with those seen by other cornea imaging methods. Cellular-level details in the images obtained together with the relatively large field-of-view (FOV) and contactless way of imaging make this device a promising candidate for becoming a new tool in ophthalmological diagnostics.
According to the World Health Organization (WHO), corneal diseases alongside with cataract and retinal diseases are major causes of blindness worldwide. For the 95.5% of corneal blindness cases, prevention or rehabilitation could have been possible without negative consequences for vision, provided that disease is diagnosed early. However, diagnostics at the early stage requires cellular-level resolution, which is not achieved with routinely used Slit-lamp and OCT instruments. Confocal microscopy allows examination of the cornea at a resolution approaching histological detail, however requires contact with a patient’s eye. The recently developed full-field OCT technique, in which 2D en face tangential optical slices are directly recorded on a camera, was successfully applied for ex vivo eye imaging. However, in vivo human eye imaging has not been demonstrated yet. Here we present a novel non-contact full-field OCT system, which is capable of imaging in air and, therefore, shows potential for in vivo cornea imaging in patients. The first cellular-level resolution ex vivo images of cornea, obtained in a completely non-contact way, were demonstrated. We were able to scan through the entire cornea (400 µm) and resolve epithelium, Bowman’s layer, stroma and endothelium. FFOCT images of the human cornea in vivo were obtained for the first time. The epithelium structures and stromal keratocyte cells were distinguishable. Both ex vivo and in vivo images were acquired with a large (1.26 mm x 1.26 mm) field of view. Cellular details in obtained images make this device a promising candidate for realization of high-resolution in vivo cornea imaging.
Non-melanoma skin cancer (NMSC) is the most common cancer. Treatment consists of surgical removal of the skin cancer. Traditional excision involves the removal of the visible skin cancer with a significant margin of normal skin. On cosmetically sensitive areas, Mohs micrographic tissue is the standard of care. Mohs uses intraoperative microscopic margin assessment which minimizes the surgical defect and can help reduce the recurrence rate by a factor of 3. The current Mohs technique relies on frozen section tissue slide preparation which significantly lengthens operative time and requires on-site trained histotechnicians. Full-Field Optical Coherence Tomography (FFOCT) is a novel optical imaging technique which provides a quick and efficient method to visualize cancerous areas in minutes, without any preparation or destruction of the tissue. This study aimed to evaluate the potential of FFOCT for the analysis of skin cancer margins during Mohs surgery.
Over 150 images of Mohs specimens were acquired intraoperatively with FFOCT before frozen section analysis. The imaging procedure took less than 5 minutes for each specimen. No artifacts on histological preparation were found arising from FFOCT manipulation; however frozen section artifact was readily seen on FFOCT. An atlas was established with FFOCT images and corresponding histological slides to reveal FFOCT reading criteria of normal and cancerous structures. Blind analysis showed high concordance between FFOCT and histology.
FFOCT can potentially reduce recurrence rates while maintaining short surgery times, optimize clinical workflow, and decrease healthcare costs. For the patient, this translates into smaller infection risk, decreased stress, and better comfort.
Transurethral resections are commonly used for bladder cancer diagnosis, treatment and follow-up. Cancer staging relies
largely on the analysis of muscle in the resections; however, muscle presence is uncertain at the time of the resection. An
extemporaneous quality control tool would be of great use to certify the presence of muscle in the resection, and
potentially formulate a primo-diagnosis, in order to ensure optimum patient care. Full-field optical coherence
tomography (FFOCT) offers a fast and non-destructive method of obtaining images of biological tissues at ultrahigh
resolution (1μm in all 3 directions), approaching traditional histological sections. This study aimed to evaluate the
potential of FFOCT for the quality control and the primo-diagnosis of transurethral bladder resections. Over 70
transurethral bladder resections were imaged with FFOCT within minutes, shortly after excision, and before histological
preparation. Side-by-side comparison with histology allowed to establish reading criteria for the presence of muscle and
cancer in particular. Images of 24 specimens were read blindly by three non-pathologists readers: two resident urologists
and a junior bio-medical engineer, who were asked to notify the presence of muscle and tumor. Results showed that after
appropriate training, 96% accuracy could be obtained on both tumour and muscle detection. FFOCT is a fast and nondestructive
imaging technique that provides analysis results concordant with histology. Its implementation as a quality
control and primo-diagnosis tool for transurethral bladder resections in the urology suite is feasible and lets envision high
value for the patient.
Full-field optical coherence tomography (FFOCT) offers a non-invasive method of obtaining images of biological tissues at ultrahigh resolution (1µm in all 3 directions) approaching traditional histological sections. Previous clinical studies have shown the high efficiency of this imaging technique for the detection of cancer on various organs. This promises great potential of the technique for an ex-vivo quick analysis of surgical resections or biopsy specimens, in the aim to help the surgeon/radiologist decide on the course of action.
Here we will present some of the latest technical developments on a FFOCT system which can produce 1cm2 images with 1 µm resolution in 1 minute. Larger samples, up to 50mm diameter, can also be imaged. Details on the large sample handling, high-speed image acquisition, optimized scanning, and accelerated GPU tiles stitching will be given. Results on the clinical applications for breast, urology, and digestive tissues will also be given. They highlight the relevance of the system characteristics for the detection of cancer on ex-vivo specimens.
FFOCT now appears clearly as a very fast and non-destructive imaging technique that provides a quick assessment of the tissue morphology. With the benefit of both new technical developments and clinical validation, it turned into a mature technique to be implemented in the clinical environment. In particular, the technique holds potential for the fast ex-vivo analysis of excision margins or biopsies in the operating room.
FFOCT (Full Field Optical Coherence Tomography) is a novel optical technology that gives access to very high resolution tomography images of biological tissues within minutes, non-invasively. This makes it an attractive tool to bridge the gap between medical imaging modalities (MRI, ultrasound, CT) used for cancer lesion identification or targeting and histological diagnosis. Clinical tissue specimens, such as surgical cancer margins or biopsies, can potentially be assessed rapidly, by the clinician, in the aim to help him decide on the course of action.
A fast FFOCT prototype was built, that provides 1cm2 images with 1 µm resolution in 1 minute, and can accommodate samples up to 50mm diameter. Specific work was carried out to implement a large sample holder, high-speed image acquisition system, optimized scanning, and accelerated GPU tiles stitching. Results obtained on breast, urology, and digestive tissues show the efficiency of the technique for the detection of cancer on clinical tissue specimens, and reinforce the clinical relevance of the technique.
The technical and clinical results show that the fast FFOCT system can successfully be used for a fast assessment of cancer excision margins or biopsies providing a very valuable tool in the clinical environment.
Full-field optical coherence tomography (FFOCT) offers a fast and non-destructive method of obtaining images of
biological tissues at ultrahigh resolution, approaching traditional histological sections. In the context of prostate cancer
diagnosis involving multiple biopsies, FFOCT could be used to validate the cores just after they are obtained in order to
guide the number of biopsies to be performed. The aim of the study was to define and test a training protocol for efficient
FFOCT prostate biopsy assessment. Three readers (a pathologist with previous experience with FFOCT, a pathologist
new to FFOCT, and a urologist new to FFOCT) were trained to read FFOCT images of prostate biopsies on a set of 20
commented zooms (1 mm field of view) and 25 complete images. They were later tested on a set of 115 anonymized and
randomized images of prostate biopsies. The results showed that an extra 30 images were necessary for more complete
training as compared to prior studies. After training, pathologists obtained 100% sensitivity on high-grade cancer
detection and 96% overall specificity; the urologist obtained 88% sensitivity on high-grade cancer and 89% overall
specificity. Overall, the readers obtained a mean of 93% accuracy of qualifying malignancy on prostate biopsies.
Moreover, the two pathologists showed a steeper learning curve than the urologist. This study demonstrates that a
training protocol for such a new imaging modality may be implemented and yield very high efficiency for the pre-histologic
detection of malignancy on prostate biopsies.
Full-field optical coherence tomography (FFOCT) quickly produces images that resemble conventional pathology images. We examined endometrium in an intra-operative like fashion (more than forty samples). FFOCT-imaged endometrium was recognizable to pathologists and compared favorably with microscopy of the same samples. Additional image enhancements and acquisition techniques were explored and may improve interpretation accuracy. Wider evaluation of images is ongoing, using more pathologist subjects. FFOCT may revolutionize pathology practice in the future by permitting rapid diagnosis and in vivo diagnosis; this is potentially a disruptive new diagnostic technique in pathology.
Optical coherence tomography (OCT) has been recently proposed by a number of laboratories as a promising tool for fingerprints acquisitions and for fakes discrimination. Indeed OCT being a non-contact, non-destructive optical method that virtually sections the volume of biological tissues that strongly scatter light it appears obvious to use it for fingerprints. Nevertheless most of the OCT setups have to go through the long acquisition of a full 3D image to isolate an “en-face” image suitable for fingerprint analysis. A few “en-face” OCT approaches have been proposed that use either a complex 2D scanning setup and image processing, or a full-field illumination using a camera and a spatially coherent source that induces crosstalks and degrades the image quality. We show here that Full Field OCT (FFOCT) using a spatially incoherent source is able to provide “en-face” high quality optical sectioning of the fingers skin. Indeed such approach shows a unique spatial resolution able to reveal a number of morphological details of fingerprints that are not seen with competing OCT setups. In particular the cellular structure of the stratum corneum and the epidermis-dermis interface appear clearly. We describe our high-resolution (1 micrometer, isotropic) setup and show our first design to get a large field of view while keeping a good sectioning ability of about 3 micrometers. We display the results obtained using these two setups for fingerprints examination.
Full-field OCT (FFOCT) has the ability to provide en-face images with a very good axial sectioning as well as a very
high transverse resolution (about 1 microns in all directions). Therefore it offers the possibility to visualize biological
tissues with very high resolution both on the axial native view, and on vertical reconstructed sections. Here we
investigated the potential dermatological applications of in-vivo skin imaging with FFOCT.
A commercial FFOCT device was adapted for the in-vivo acquisition of stacks of images on the arm, hand and finger.
Several subjects of different benign and pathological skin conditions were tested. The images allowed measurement of
the stratum corneum and epidermis thicknesses, measurement of the stratum corneum refractive index, size measurement
and count of the keratinocytes, visualization of the dermal-epidermal junction, and visualization of the melanin granules
and of the melanocytes. Skins with different pigmentations could be discriminated and skin pathologies such as eczema
could be identified.
The very high resolution offered by FFOCT both on axial native images and vertical reconstructed sections allows for
the visualization and measurement of a set of parameters useful for cosmetology and dermatology. In particular, FFOCT
is a potential tool for the understanding and monitoring of skin hydration and pigmentation, as well as skin inflammation.
Optical Coherence Tomography (OCT) is an efficient technique for in-depth optical biopsy of biological tissues, relying
on interferometric selection of ballistic photons. Full-Field Optical Coherence Tomography (FF-OCT) is an alternative
approach to Fourier-domain OCT (spectral or swept-source), allowing parallel acquisition of en-face optical sections.
Using medium numerical aperture objective, it is possible to reach an isotropic resolution of about 1x1x1 ìm. After
stitching a grid of acquired images, FF-OCT gives access to the architecture of the tissue, for both macroscopic and
microscopic structures, in a non-invasive process, which makes the technique particularly suitable for applications in
pathology. Here we report a multimodal approach to FF-OCT, combining two Full-Field techniques for collecting a
backscattered endogeneous OCT image and a fluorescence exogeneous image in parallel. Considering pathological
diagnosis of cancer, visualization of cell nuclei is of paramount importance. OCT images, even for the highest resolution,
usually fail to identify individual nuclei due to the nature of the optical contrast used. We have built a multimodal optical
microscope based on the combination of FF-OCT and Structured Illumination Microscopy (SIM). We used x30 immersion objectives, with a numerical aperture of 1.05, allowing for sub-micron transverse resolution. Fluorescent staining of nuclei was obtained using specific fluorescent dyes such as acridine orange. We present multimodal images of healthy and pathological skin tissue at various scales. This instrumental development paves the way for improvements of standard pathology procedures, as a faster, non sacrificial, operator independent digital optical method compared to frozen sections.
The Applied Optics group at the National University of Ireland, Galway, is engaged in research into various aspects of
the application of adaptive optics to both ocular and atmospheric wavefront correction. A large number of commercially available deformable mirrors have been selected by the group for AO experiments, and these mirrors have been carefully characterised to determine their suitability for these tasks. In this paper we describe the approach we have used in characterising deformable mirrors and present results for several MEMs mirrors, including membrane mirrors from AgilOptics and Flexible Optical BV, a segmented micromirror from IrisAO and a 140-actuator mirror from Boston micromachines.
A performance comparison is made using a number of commercially available Deformable Mirrors(DM) in fitting
both ocular and atmospheric wavefronts. Least squares phase fitting simulations are performed for five mirrors
using experimentally obtained mirror influence functions. The DMs used cover a range of DM technologies with
varying size and cost. The phase fitting performance of these mirrors is found to be a function of influence
function shape, actuator density and available mirror stroke.
MEMS is one of several emerging technologies for fabricating wavefront correctors for use in adaptive optics systems. Each technology has its own advantages and disadvantages. In order to compare devices, it is useful to define a task and make a comparison based upon the effectiveness of each device for this task. Such an approach implies, of course, that device A might be better suited for task X whereas device B is better suited for task Y. In adaptive optics, this situation is already known: deformable mirrors that are relatively effective at compensating for atmospheric turbulence are not necessarily the mirrors that one would choose for correction of the aberrations of the eye. This is essentially because the statistical modal distribution of the aberrated wavefronts in each case are different. In this talk, we shall present a method for systematically evaluating the effectiveness of different mirror (or transmissive) technologies in adaptive optics in the eye. It uses a model for the aberrations of the eye (such as that developed by Thibos et al1) and a least squares fitting procedure. Results will be presented for at least 4 mirrors, including a 12x12 MEMS device. The key point is that it is the effectiveness of each actuator signal that is important, not the raw number of actuators.
Some results concerning the correction loop of an Adaptive Optics (AO) system for the eye are presented. This is part of a project aiming to study the effects of AO on visual performance, using psychophysical methods. The AO system used in the project is presented. It comprises a Shack-Hartmann sensor, which measures the light deformation after a double-pass in the eye, and two corrective blocks. A Badal optometer coupled with cylindrical lenses is used to remove the main refractive aberrations, while a deformable mirror deals with the remaining aberrations. This system can enable one to carry out psychophysical experiments as a stimulus is viewed by the
subject through the same optics. A bimorph mirror has been tested in view of correcting ocular simulations, and recently implemented in the system. The experimental results, consistent with the simulations, yield to a residual root-mean-square wavefront deviation of about 0.06 microns over a 4.8 mm pupil, corresponding to a Strehl ratio of approximately 0.6.
This paper reviews the highlights of the high intensity laser-plasma experiments achieved with the six-beam and the 100 TW LULI laser facilities, as well as the progress of the LULI 2000 project. This covers fields of laser fusion, equations of state, hgih energy particle emission, atomic physics, X-ray production and laser developments.
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