We present a novel ultrafast imaging system using Spatio-Temporal Optical Coherence Tomography (STOC-T), capable of acquiring structural images of a mouse retina at a volumetric rate of 112 Hz, aided by a calibrated fundus camera for focal plane adjustment. We extract blood pulse traces from retinal and choroidal vessels using a structural-only OCT analysis, and pulse wave-induced retinal layer displacement from differential OCT phase analysis. With both analyses, we measure hemodynamic parameters, such as the delays between arterial and venous pulsation, to provide a comprehensive suite of potential biomarkers of retinal diseases.
The progress made in optical coherence tomography (OCT) has facilitated the noninvasive observation of biological structures. While Fourier-Domain Full-Field OCT (FD-FF-OCT) enables rapid collection of volumetric data, it encounters challenges arising from coherent noise. To tackle this issue, we introduced STOC-T ľ spatial-temporal optical coherence tomography, which utilizes spatial phase modulation alleviate crosstalk interference. This research thoroughly investigates the characteristics of optical fibers in the context of STOC-T, crafted for volumetric imaging and the mitigation of coherent crosstalk noise. We assess the effects of multimode fibers and execute a performance analysis employing a purpose-designed scattering phantom. Our presentation encompasses detailed insights into the experimental arrangement and outcomes, emphasizing noise reduction. We also explore hurdles like determining the ideal fiber length, analyzing speckle patterns, and ensuring signal quality. Through a meticulous selection process of multimode fibers, we amplify the potential of STOC-T for structural and functional retinal imaging.
The absence of confocal gating in full-field Optical Coherence Tomography (OCT) worsens its dynamic range and thereby the sensitivity and signal to background noise ratio because of the inability to reject the out-of-focus and other incoherent light. Here, we present a simple and affordable confocal line scanning implementation that significantly reduces the incoherent light. We realize a fully digital line scanning that contains no moving parts, by exploiting a Digital Mirror Device (DMD) in combination with a CMOS camera running in the rolling shutter mode. An improvement of the signal to noise ratio due to the confocal line-scanning by at least an order of magnitude was demonstrated on a sample composed of the USAF target mounted behind a scattering layer. We also imaged a sample of onion epidermis with an incoherent reflector.
We developed and applied Spatio-Temporal Optical Coherence Tomography (STOC-T), which supported by computational aberration correction enables high resolution imaging of the human and mouse retina in vivo.
Spatio-Temporal Optical Coherence Tomography (STOC-T) is a new imaging modality that uses light with controlled spatial and temporal coherence. The retinal images acquired with the STOC-T system maintain high resolution in all three dimensions, over the entire thickness of about 700 μm, without mechanical scanning. We have employed known data processing algorithms and developed new ones to handle and process the acquired data sets to produce highly corrected 3D data for retinas over large fields of view. The technology and algorithms used here enabled high transverse resolution imaging of the retina and the choroid at various depths, making the differentiation of morphology visible for the first time within the Sattler’s, Haller’s, and choriocapillaris layers. Visualization of choroidal layers was carried out by using the STOCT angio algorithm. We analyzed the acquired data quantitatively to identify an effective biomarker.
We present a novel ultrafast imaging system using Spatio-Temporal Optical Coherence Tomography (STOC-T), capable of acquiring structural images of a mouse retina at a volumetric rate of 112 Hz. A calibrated fundus camera and white-light illumination aid the alignment of the mouse and the adjustment of the focal plane in the mouse retina for the STOC-T image. We extract pulsatile blood flow frequency and other hemodynamic parameters from multiple retinal and choroidal vessels from structural-only OCT images, highlighting the prospects of STOC-T for monitoring retinal hemodynamics in a simple way.
We present an optical imaging system, termed Spatio-Temporal Optical Coherence Tomography, for high-resolution and fast in vivo imaging of chorioretinal complex. The system utilizes a fast camera and a swept laser source for fast volumetric data acquisition. A multimode fiber is used to break the spatial coherence of the laser that reduces the crosstalk noise in the OCT images. We choose the fiber parameters such that it gives the most optimal images in terms of signal strength, resolution and crosstalk reduction. We also test combinations of the fiber with other optomechanical devices in the attempt to further improve the images.
We present a novel mouse eye imaging system based on the Spatio-Temporal Optical Coherence Tomography (STOC-T) technique capable of acquiring structural image of a mouse retina at a volumetric rate of 112 Hz. A fundus camera and white light illumination aid the alignment of the mouse and the adjustment of the focal plane in the mouse retina for the STOC-T image. The fundus camera is calibrated so that when the white-light image of the mouse eye fundus appears in focus after the appropriate gel thickness is selected for a given mouse and bi-concave lens, the corresponding near infrared STOC-T image of the photoreceptor layer is also in focus, albeit with minor shifts. We present images of retinal and choroidal tissue from a B6 albino wild type mouse after the focal plane adjustment with richness of details.
We report on a novel mice imaging system based on the Spatio-Temporal Optical Coherence Tomography (STOC-T)
technique. The contribution describes the translation of the STOC-T technique, initially developed for human eye imaging, into the field of experimental small animal imaging. We present images of retinal and choroidal tissue from a B6 albino wild type mouse acquired at a volumetric rate of 112 Hz.
We recently demonstrated high-speed, high-resolution structural imaging of the human eye in vivo by spatiotemporal optical coherence tomography (STOC-T). STOC-T extends the Fourier-Domain Full-Field Optical Coherence Tomography (FD-FF-OCT) by the spatial phase modulation to improve the imaging depth and suppress coherent noises.
Here, we show that the dataset produced by STOC-T can be processed differently to reveal blood flow in the superficial and deep retina layers. Our method, denoted as multiwavelength LDH (MLDH) enables noninvasive visualization and quantification of the blood flow deep into the human retina at high speeds and high transverse resolution in vivo.
We report results from in-vivo measurements of a human retina photoreceptors layer response to a flicker stimulus. We performed our experiments with the Spatio-Temporal Optical Coherence-Tomography (STOC-T) setup. We show that the phase analysis facilitates spatially resolved detection of the retina's response to different stimulus frequencies.
Critical flicker frequency measurements are important in determining the spatial variation of flicker sensitivity in the human retina. An objective and localized measurement of the frequency response of photoreceptors could help elucidate the true physiological mechanisms responsible for such flicker sensitivity variations. Flicker optoretinography (ORG) may be a promising technique for this purpose. In this work, we use Spatio-Temporal Optical Coherence-Tomography to capture flicker optoretinograms to visible patterned light stimulation modulated in the range from few Hz to 30Hz over 5.7º x 2.8º of the retina, at several foveal eccentricities, highlighting the prospect for objective flicker perimetry with ORG.
Photoreceptors are the primary sensing element of the human visual system. Traditionally, photoreceptors are imaged with hardware-based adaptive optics (AO), which compensate for eye aberrations. However, these systems can be challenging to maintain. Here, we demonstrate the spatiotemporal optical coherence tomography
(STOC-T) as the new modality for high-speed, cellular-level volumetric imaging of the human retina in vivo. The cellular features become visible after applying digital aberration corrections. We also show that STOC-T provides cross-sectional images (B-scans) and, concurrently, high-resolution wide-field en face images of the inner and outer human retina layers.
In this contribution, we report on in vivo retinal and choroid tissue imaging with Spatio-Temporal Optical Coherence Tomography (STOC-T) with a large field of view (9 x 4.6 mm2). We present en-face images of the retina's microstructure and choroid of the human eye with resolution enabling observation of single photoreceptors and choriocapillaris.
Despite the rapid development of OCT, high-resolution in vivo imaging of human eye with penetration into deeper retinal layers and choroid is still a major challenge due to its sensitivity to coherent noise, such as speckle and crosstalk. To address that, we have developed a technique termed Spatio-Temporal Optical Coherence Tomography (STOC-T) that uses light with controlled spatial and temporal coherence to obtain high-contrasted coronal projection images of the choroid at various depths including that of choriocapillaris. It can also detect blood flow and reveal vascular networks in various chorioretinal layers that are otherwise invisible to OCT.
Spatiotemporal optical coherence (STOC) manipulation is a new method for crosstalk-free, aberration-free, high-speed, high-resolution imaging of the human eye in vivo. Here, we apply STOC for deep blood flow imaging of the human retina in vivo.
We present an optical imaging system, termed STOC-T, for retinal in vivo imaging that uses a multimode fiber for crosstalk noise reduction and a line camera for fast preview mode.
KEYWORDS: Optical coherence tomography, Retina, Data acquisition, In vivo imaging, Digital micromirror devices, Optical testing, Optical filters, Multimode fibers, Light emitting diodes, Imaging systems
In this paper, we present in vivo optoretinography using a Spatio-Temporal Optical Coherence Tomography STOC-T setup. With our system, we were able to detect both fast and slow responses to a light stimulus.
KEYWORDS: Spatial coherence, Optical coherence tomography, Eye, Cameras, Retina, Data acquisition, Line scan cameras, In vivo imaging, Ultrafast imaging, Sensors
We characterize the engineering of spatial coherence for STOC-T. We present large field-of-view (9x4.6 mm) images of the retina's microstructure and choroid of the human eye with resolution enabling observation of single photoreceptors and choriocapillaries.
Fourier-domain full-field optical coherence tomography (FD-FF-OCT) is currently the fastest volumetric imaging technique that is able to generate a single 3D data volume in less than 10 ms. FD-FF-OCT is based on a fast camera, a rapidly tunable laser source and a Fourier-domain signal detection. However, crosstalk corrupts images with speckle and therefore lowers image quality. Corneal imaging with FD-FF-OCT is also challenging since the laser focuses down on the retina causing safety concerns. We present spatially incoherent FD-FF-OCT system that reduces crosstalk noise in retina images and enables corneal imaging by reducing spatial coherence of the laser.
Optical coherence tomography (OCT) is a well-established modality providing cross-sectional images of the human retina. OCT, however, does not provide high-resolution en face images of the outer retinal layers due to eye aberrations and the tradeoff between imaging depth and transverse resolution. Recently, we demonstrated the spatiotemporal optical coherence (STOC) that provides high-resolution, aberration-free volumetric images of the retina and cornea with the voxel rate of 8 GHz. Here, we show that STOC can be used for angiography, and allows us to estimate Doppler broadening, enabling visualization of the choroidal blood vessels in the human retina in vivo.
We apply spatiotemporal optical coherence (STOC) manipulation with digital aberration correction to achieve aberration-free, crosstalk-free, high-speed, high-resolution Fourier-domain full-field optical coherence tomography (FD-FF-OCT). We demonstrate structural imaging of the human retina and cornea, and the blood flow imaging of the human retina in vivo.
Spatiotemporal optical coherence (STOC) imaging is a novel technique for suppressing coherent cross-talk noise in full-field swept-source OCT (FF-SS-OCT). In STOC, we use time-varying phase masks to modulate light incident on the sample. The modulated signals are averaged incoherently or coherently to yield cross-talk-free 3D images of the sample. We show that coherent averaging is only possible under specific hardware configuration. We explain this theoretically and confirm experimentally by imaging USAF chart covered by diffusers and the rat skin ex vivo. Finally, we present human forearm skin imaging in vivo. In all cases, STOC imaging reveals otherwise invisible sample features.
Optical coherence tomography (OCT) has become a useful skin imaging tool in recent years. It can be used to image skin structure with great detail and deep below the surface. However, there is an unmet need for an inexpensive device that would be able to acquire high-quality en face images in short time. To this end, we report on a cost-effective full-field optical coherent tomography (FF-OCT) system comprised of a silicon camera with high full well capacity and a powerful near-infrared LED light source. The system, for example, is able to record 1.7 cm × 1.7 cm en face images in 0.12 sec with the spatial sampling rate of 2116 dpi and the sensitivity of 93 dB. We show that the FF-OCT system can be used for biometrics purposes by imaging internal fingerprints and sweat ducts with a good contrast and in short-enough time. Blood flow can also be sensed in dermis that, for example, can be used for liveness detection. The developed instrument could also be used in other en face deep-tissue imaging applications because of its high sensitivity and speed. One particular application is passive elastography that can map the stiffness of biological tissues. We will also present FF-OCT configurations that help improving the imaging depth through rejection of specular reflections and better use of a light budget.
Images recorded below the surface of a finger can have more details and be of higher quality than the conventional surface fingerprint images. This is particularly true when the quality of the surface fingerprints is compromised by, for example, moisture or surface damage. However, there is an unmet need for an inexpensive fingerprint sensor that is able to acquire high-quality images deep below the surface in short time. To this end, we report on a cost-effective full-field optical coherent tomography system comprised of a silicon camera and a powerful near-infrared LED light source. The system, for example, is able to record 1.7 cm×1.7 cmen face images in 0.12 s with the spatial sampling rate of 2116 dots per inch and the sensitivity of 93 dB. We show that the system can be used to image internal fingerprints and sweat ducts with good contrast. Finally, to demonstrate its biometric performance, we acquired subsurface fingerprint images from 240 individual fingers and estimated the equal-error-rate to be ∼0.8%. The developed instrument could also be used in other en face deep-tissue imaging applications because of its high sensitivity, such as in vivo skin imaging.
We present a stimulated emission depletion (STED) fluorescence lifetime imaging (FLIM) microscope, excited by a
microstructured optical fibre supercontinuum source that is pumped by a femtosecond Ti:Sapphire-laser, which is also
used for depletion. Implemented using a piezo-scanning stage on a laser scanning confocal fluorescence microscope
system with FLIM realised using time correlated single photon counting (TCSPC), this provides convenient switching
between confocal and STED-FLIM with spatial resolution down to below 60 nm. We will present our design
considerations to make a robust instrument for biological applications including a comparison between fixed phase plate
and spatial light modulator (SLM) approaches to shape the STED beam and the correlation of STED and confocal FLIM
microscopy. Following our previous application of FLIM-FRET to study intercellular signalling at the immunological
synapse (IS), we are employing STED microscopy to characterize the spatial distribution of cellular molecules with subdiffraction
resolution at the IS. In particular, we are imaging cytoskeletal structure at the Natural Killer cell activated
immune synapse. We will also present our progress towards multilabel STED microscopy to determine how relative
spatial molecular organization, previously undetectable by conventional microscopy techniques, is important for NK cell
cytotoxic function. Keywords: STED, Stimulated Emission Depletion Microscopy, Natural Killer (NK) cell,
Fluorescence lifetime imaging, FLIM, Super resolution microscopy.
We describe the characterisation of a hyperspectral fluorescence lifetime imaging microscope that exploits high-speed
time-gated imaging technology and a tunable continuum source for 6-D fluorescence imaging. This line-scanning
confocal microscope can record the full spectral-temporal (i.e. excitation-emission-lifetime) fluorescence matrix at each
pixel in a three dimensional (x-y-z) sample. This instrument has been applied to biological samples including model
membranes and live cells labelled with the phase-sensitive membrane dye di-4-ANEPPDHQ, for which significant
variation of lifetime with emission wavelength is observed.
Permanent infections recognized as oncogenic factor. STD is common concomitant diseases in early precancerous genital tract lesions. Simple optical detection of early regressive pre cancer in cervix is the aim of this study. Hereditary immunosupression most likely is risk factor for cervical cancer development. Light induced fluorescence point monitoring fitted to live cervical tissue diagnostics in 42 patients. Human papilloma virus DNR in cervix tested by means of Hybrid Capture II method. Ultraviolet (337 nm) laser excited fluorescence spectra in the live cervical tissue analyzed by Principal Component (PrC) regression method and spectra decomposition method. PCr method best discriminated pathology group "CIN I and inflammation"(AUC=75%) related to fluorescence emission in short wave region. Spectra decomposition method suggested a few possible fluorophores in a long wave region. Ultraviolet (398 nm) light excitation of live cervix proved sharp selective spectra intensity enhancement in region above 600nm for High-grade cervical lesion. Conclusion: PC analysis of UV (337 nm) light excitation fluorescence spectra gives opportunity to obtain local immunity and Low-grade cervical lesion related information. Addition of shorter and longer wavelengths is promising for multi wave LIF point monitoring method progress in cervical pre-cancer diagnostics and utility for cancer prevention especially in developing countries.
Multi-beam confocal sectioned fluorescence lifetime imaging microscopy is demonstrated using a Yokogawa spinning disk. The single-photon excitation source is a supercontinuum generated from a Ti:sapphire seeded photonic crystalline fibre.
Lanthanide-ion doped oxide nanoparticles were functionalized for use as fluorescent biological labels. These nanoparticles are synthesized directly in water which facilitates their functionalization, and are very photostable without emission intermittency. Nanoparticles functionalized with guanidinium groups act as artificial toxins and specifically target sodium channels. They are individually detectable in cardiac myocytes, revealing a heterogeneous distribution of sodium channels. Functionalized oxide nanoparticles appear as a novel tool particularly well adapted to long-term single-molecule tracking.
We have analysed an endometrial tissue fluorescence excitation spectra with a purpose to determine the characteristic wavelength of excitation for multiwavelength diagnostics of tissue. Fluorescence excitation-emission matrices from 200 to 500 nm excitation and 200 to 800 nm emission were measured as a supplementary data for previous measurements to unambiguously characterize biochemicals quantitatively in endometrial tissue.
The aim of this study was to assess the feasibility of autoflorescence spectroscopy in the diagnosis of cervix maturity through cervical mucus florescence and foetal lung maturity through amniotic fluid fluorescence. LED and broadband Mercury light were used to induce fluorescence in cervical mucus and amniotic fluid respectively. Mature specimens compared to immature ones showed a significant decrease in cervical mucus fluorescence values measured at 420 nm (p = 0.0004) and in measured amniotic fluid fluorescence values at 410 nm (p = 0.0686). Probability-based classification algorithm was developed to identify samples 'maturity' through analysis of the fluorescence spectra. Employing fluorescence intensity at 420 nm for cervix maturity diagnosis rendered optimal sensitivity of 92.9%, specificity of 83.3% and area under the ROC curve of 91.1%.
An effort has been made to detect neopterin spectrum in fluorescence of premalignant endometrial tissue and to estimate the number of fluorophores naturally existing in the tissue with fluorescence present above the noise level. Endometrial Tissue fluorescence was measured in vitro by excitation with the third harmonic of Nd YAG laser. Multivariate curve resolution was used for testing neopterin presence in endometrial tissue. Fluorescence spectra ofneopterin was measured and used as a target spectrum for testing. Seven factors -fluorescence ofnatural fluorophores ofendometrial tissue were found to be present above the noise level in the overall autofluorescence. Neopterin concentration may be too low in endometrial tissue
to make its fluorescence above the noise level because neopterin spectrum was not found to be among the spectra resolved by multivariate curve resolution. An intensity increase in the neopterin spectrum spectral region in hyperplastic endometrial samples might be associated with neopterin concentration increase.
Background and Objective: The detailed multivariate analysis of endometrial tissue fluorescence spectra was done. Spectra underlying features and classification algorithm were analyzed. An effort has been made to determine the importance of neopterin component in endometrial premalignization.
Study Design/Materials and Methods: Biomedical tissue fluorescence was measured by excitation with the Nd YAG laser third harmonic. Multivariate analysis techniques were used to analyze fluorescence spectra. Biomedical optics group at Vilnius University analyzed the neopterin substance supplied by the Institute of Medical Chemistry and Biochemistry of Innsbruck University.
Results: Seven statistically significant spectral compounds were found. The classification algorithm classifying samples to histopathological categories was developed and resulted in sensitivity of 80% and specificity 93% for malignant vs. hyperplastic and normal.
Conclusions: Fluorescence spectra could be classified with high accuracy. Spectral variation underlying features can be extracted.
Neopterin component might play an important role in endometrial hyperplasia development.
The detailed statistical analysis of the tissue fluorescence spectra was proposed for the investigation of tissue biochemical changes. The method is based on the decomposition of the autofluorescence spectrum into the spectra of natural components of cells. The human tissues with different physiological activity or affected by sickness were investigated. The tissue spectra changes are grouped by the histology data. The observed correlation of fluorescence spectra structure changes for cancer and other 'normal' phases of the tissue are observed from multivariate statistical analysis.
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.