1. Articles from Aneesh Alex

    1-20 of 20
    1. Investigating the healing mechanisms of an angiogenesis-promoting topical treatment for diabetic wounds using multimodal microscopy

      Investigating the healing mechanisms of an angiogenesis-promoting topical treatment for diabetic wounds using multimodal microscopy

      Impaired skin wound healing is a significant co-morbid condition of diabetes that is caused by poor microcirculation, among other factors. Studies have shown that angiogenesis, a critical step in the wound healing process in diabetic wounds, can be promoted under hypoxia. In this study, an angiogenesis-promoting topical treatment for diabetic wounds, which promotes angiogenesis by mimicking a hypoxic environment via inhibition of prolyl hydroxylase resulting in elevation or maintenance of hypoxia inducible factor (HIF), was investigated utilizing a custom-built multimodal microscopy system equipped with phase-variance optical coherence tomography (PV-OCT) and fluorescence lifetime imaging microscopy (FLIM). PV-OCT was used to track ...

      Read Full Article
    2. Optical Coherence Tomography for Brain Imaging and Developmental Biology

      Optical Coherence Tomography for Brain Imaging and Developmental Biology

      Optical coherence tomography (OCT) is a promising research tool for brain imaging and developmental biology. Serving as a three-dimensional optical biopsy technique, OCT provides volumetric reconstruction of brain tissues and embryonic structures with micrometer resolution and video rate imaging speed. Functional OCT enables label-free monitoring of hemodynamic and metabolic changes in the brain in vitro and in vivo in animal models. Due to its noninvasiveness nature, OCT enables longitudinal imaging of developing specimens in vivo without potential damage from surgical operation, tissue fixation and processing, and staining with exogenous contrast agents. In this paper, various OCT applications in brain imaging ...

      Read Full Article
    3. Label-Free Imaging of Eosinophilic Esophagitis Mouse Models Using Optical Coherence Tomography

      Label-Free Imaging of Eosinophilic Esophagitis Mouse Models Using Optical Coherence Tomography

      Eosinophilic esophagitis (EoE) is an immune-mediated disorder characterized by esophageal inflammation and related structural changes causing symptoms such as feeding difficulties and food impaction. The pathophysiological mechanisms underlying EoE remain poorly understood. Preclinical studies using mouse models have been critical in comprehending human disease mechanisms and associated pathways. In this chapter, we describe an experimental method using a noninvasive label-free optical imaging technique, optical coherence tomography, to characterize the pathophysiological changes in the esophagus of mice with EoE-like disease ex vivo.

      Read Full Article
    4. Optogenetic pacing in Drosophila melanogaster

      Optogenetic pacing in Drosophila melanogaster

      Electrical stimulation is currently the gold standard for cardiac pacing. However, it is invasive and nonspecific for cardiac tissues. We recently developed a noninvasive cardiac pacing technique using optogenetic tools, which are widely used in neuroscience. Optogenetic pacing of the heart provides high spatial and temporal precisions, is specific for cardiac tissues, avoids artifacts associated with electrical stimulation, and therefore promises to be a powerful tool in basic cardiac research. We demonstrated optogenetic control of heart rhythm in a well-established model organism, Drosophila melanogaster . We developed transgenic flies expressing a light-gated cation channel, channelrhodopsin-2 (ChR2), specifically in their hearts and ...

      Read Full Article
    5. A Circadian Clock Gene, Cry, Affects Heart Morphogenesis and Function in Drosophila as Revealed by Optical Coherence Microscopy

      A Circadian Clock Gene, Cry, Affects Heart Morphogenesis and Function in Drosophila as Revealed by Optical Coherence Microscopy

      Circadian rhythms are endogenous, entrainable oscillations of physical, mental and behavioural processes in response to local environmental cues such as daylight, which are present in the living beings, including humans. Circadian rhythms have been related to cardiovascular function and pathology. However, the role that circadian clock genes play in heart development and function in a whole animal in vivo are poorly understood. The Drosophila cryptochrome (dCry) is a circadian clock gene that encodes a major component of the circadian clock negative feedback loop. Compared to the embryonic stage, the relative expression levels of dCry showed a significant increase (>100-fold) in ...

      Read Full Article
    6. Photonic integrated Mach-Zehnder interferometer with an on-chip reference arm for optical coherence tomography

      Photonic integrated Mach-Zehnder interferometer with an on-chip reference arm for optical coherence tomography

      Optical coherence tomography (OCT) is a noninvasive, three-dimensional imaging modality with several medical and industrial applications. Integrated photonics has the potential to enable mass production of OCT devices to significantly reduce size and cost, which can increase its use in established fields as well as enable new applications. Using silicon nitride (Si 3 N 4 ) and silicon dioxide (SiO 2 ) waveguides, we fabricated an integrated interferometer for spectrometer-based OCT. The integrated photonic circuit consists of four splitters and a 190 mm long reference arm with a foot-print of only 10 × 33 mm 2 . It is used as the core of ...

      Read Full Article
    7. Characterization of eosinophilic esophagitis murine models using optical coherence tomography

      Characterization of eosinophilic esophagitis murine models using optical coherence tomography

      Pre-clinical studies using murine models are critical for understanding the pathophysiological mechanisms underlying immune-mediated disorders such as Eosinophilic esophagitis (EoE). In this study, an optical coherence tomography (OCT) system capable of providing three-dimensional images with axial and transverse resolutions of 5 µm and 10 µm, respectively, was utilized to obtain esophageal images from a murine model of EoE-like disease ex vivo . Structural changes in the esophagus of wild-type ( Tslpr +/+ ) and mutant ( Tslpr −/− ) mice with EoE-like disease were quantitatively evaluated and food impaction sites in the esophagus of diseased mice were monitored using OCT. Here, the capability of OCT as a ...

      Read Full Article
    8. Feature Of The Week 9/22/13: Lehigh University Researchers Investigate Space-Division Multiplexing for High-Speed Optical Coherence Tomography

      Feature Of The Week 9/22/13: Lehigh University Researchers Investigate Space-Division Multiplexing for High-Speed Optical Coherence Tomography

      High speed, high resolution and high sensitivity are desirable for optical coherence tomography (OCT). Here, we demonstrate a space-division multiplexing (SDM) technology that translates long coherence length of a commercially available wavelength tunable laser into high OCT imaging speed. We achieved an effective 800,000 A-scans/s imaging speed using a commercially available 100,000 Hz tunable vertical cavity surface-emitting laser (VCSEL) from Thorlabs Inc. A sensitivity of 94.6 dB and a roll-off of < 2 dB over ~30 mm imaging depth were measured in the prototype SDM-OCT system. An axial resolution of ~11 m in air (or ~8.3 ...

      Read Full Article
    9. Space-division multiplexing optical coherence tomography

      Space-division multiplexing optical coherence tomography

      High speed, high resolution and high sensitivity are desirable for optical coherence tomography (OCT). Here, we demonstrate a space-division multiplexing (SDM) technology that translates long coherence length of a commercially available wavelength tunable laser into high OCT imaging speed. We achieved an effective 800,000 A-scans/s imaging speed using a 100,000 Hz tunable vertical cavity surface-emitting laser (VCSEL). A sensitivity of 94.6 dB and a roll-off of < 2 dB over ~30 mm imaging depth were measured from a single channel in the prototype SDM-OCT system. An axial resolution of ~11 μm in air (or ~8.3 μm ...

      Read Full Article
    10. Measurement of Tear Film Thickness Using Ultrahigh Resolution Optical Coherence Tomography

      Measurement of Tear Film Thickness Using Ultrahigh Resolution Optical Coherence Tomography

      Purpose: To visualize the pre-corneal tear film with high resolution spectral domain optical coherence tomography, enabling quantification of tear film thickness in healthy subjects. Methods: A custom built spectral domain optical coherence tomography system comprising a broad band Ti:Sapphire laser operating at 800 nm and a high speed CCD camera with a read out rate of 47 kHz was used for measurement of pre-corneal tear film thickness. The system provides an axial resolution of 1.2 µm in tissue. A total of 26 healthy subjects were included in this study. Measurement was started immediately after blinking and averaged over ...

      Read Full Article
    11. In situ structural and microangiographic assessment of human skin lesions with high-speed OCT

      In situ structural and microangiographic assessment of human skin lesions with high-speed OCT

      We demonstrate noninvasive structural and microvascular contrast imaging of different human skin diseases in vivo using an intensity difference analysis of OCT tomograms. The high-speed swept source OCT system operates at 1310 nm with 220 kHz A-scan rate. It provides an extended focus by employing a Bessel beam. The studied lesions were two cases of dermatitis and two cases of basal cell carcinoma. The lesions show characteristic vascular patterns that are significantly different from healthy skin. In case of inflammation, vessels are dilated and perfusion is increased. In case of basal cell carcinoma, the angiogram shows a denser network of ...

      Read Full Article
    12. Three-dimensional multiphoton/optical coherence tomography for diagnostic applications in dermatology

      Three-dimensional multiphoton/optical coherence tomography for diagnostic applications in dermatology

      A preliminary clinical trial using state-of-the-art multiphoton tomography (MPT) and optical coherence tomography (OCT) for three-dimensional (3D) multimodal in vivo imaging of normal skin, nevi, scars and pathologic skin lesions has been conducted. MPT enabled visualization of sub-cellular details with axial and transverse resolutions of <2 μm and <0.5 μm, respectively, from a volume of 0.35 × 0.35 × 0.2 mm3 at a frame rate of 0.14 Hz (512 × 512 pixels). State-of-the-art OCT, operating at a center wavelength of 1300 nm, was capable of acquiring 3D images depicting the layered architecture of skin with axial and transverse ...

      Read Full Article
    13. Three-dimensional calibration targets for optical coherence tomography

      Three-dimensional calibration targets for optical coherence tomography

      The recent expansion of clinical applications for optical coherence tomography (OCT) is driving the development of approaches for consistent image acquisition. There is a simultaneous need for time-stable, easy-to-use imaging targets for calibration and standardization of OCT devices. We present calibration targets consisting of three-dimensional structures etched into nanoparticle-embedded resin. Spherical iron oxide nanoparticles with a predominant particle diameter of 400 nm were homogeneously dispersed in a two part polyurethane resin and allowed to harden overnight. These samples were then etched using a precision micromachining femtosecond laser with a center wavelength of 1026 nm, 100kHz repetition rate and 450 fs ...

      Read Full Article
    14. 3D optical coherence tomography for clinical diagnosis of nonmelanoma skin cancers

      3D optical coherence tomography for clinical diagnosis of nonmelanoma skin cancers

      High-resolution frequency domain optical coherence tomography (OCT) stands out amongst a range of novel dermatologic imaging technologies, with its good detection sensitivity around -100 dB, high measurement speeds allowing real-time image acquisition and its ability to acquire high definition cross-sectional and 3D tomograms of regions greater than 1 cm2, providing tissue information comparable to conventional histopathology without the need for any contrast agents. Typical axial and transverse resolutions of state-of-the-art OCT systems range between 1–10 µm and approximately 20 µm, respectively, depending on the employed wavelength region. This review investigates the significant progress accomplished in the field of dermatologic ...

      Read Full Article
    15. Multimodal photoacoustic and optical coherence tomography scanner using an all optical detection scheme for 3D morphological skin imaging

      Multimodal photoacoustic and optical coherence tomography scanner using an all optical detection scheme for 3D morphological skin imaging

      A noninvasive, multimodal photoacoustic and optical coherence tomography (PAT/OCT) scanner for three-dimensional in vivo (3D) skin imaging is described. The system employs an integrated, all optical detection scheme for both modalities in backward mode utilizing a shared 2D optical scanner with a field-of-view of ~13 × 13 mm2. The photoacoustic waves were detected using a Fabry Perot polymer film ultrasound sensor placed on the surface of the skin. The sensor is transparent in the spectral range 590-1200 nm. This permits the photoacoustic excitation beam (670-680 nm) and the OCT probe beam (1050 nm) to be transmitted through the sensor head ...

      Read Full Article
    16. In vivo response of GsdmA3Dfl/+ mice to topically applied anti-psoriatic agents: effects on epidermal thickness, as determined by optical coherence tomography and H&E staining.

      In vivo response of GsdmA3Dfl/+ mice to topically applied anti-psoriatic agents: effects on epidermal thickness, as determined by optical coherence tomography and H&E staining.

      This study evaluated in vivo the potential of optical coherence tomography (OCT) to determine changes in thickness of the epidermis in response to the topically applied anti-psoriatics betamethasone dipropionate (BD), salicylic acid (SA) and also fish oil (FO). GsdmA3Dfl/+ mice have an inflammatory hair loss phenotype that includes hyperproliferation and epidermal thickening, hence a potential psoriasis model. Changes in epidermal thickness were evaluated over a period of 10 days, with the mice treated with combined BD + SA, FO + SA and BD + FO + SA. The data were validated with conventional measurement using H&E staining coupled with microscopy. Initial baseline measurement ...

      Read Full Article
    17. In Vivo, In Situ Imaging of Microneedle Insertion into the Skin of Human Volunteers Using Optical Coherence Tomography

      In Vivo, In Situ Imaging of Microneedle Insertion into the Skin of Human Volunteers Using Optical Coherence Tomography

      Purpose  To gather sub-surface in situ images of microneedle-treated human skin, in vivo, using optical coherence tomography (OCT). This is the first study to utilise OCT to investigate the architectural changes that are induced in skin following microneedle application. Methods  Steel, silicon and polymer microneedle devices, with different microneedle arrangements and morphologies, were applied to two anatomical sites in human volunteers following appropriate ethical approval. A state-of-the-art ultrahigh resolution OCT imaging system operating at 800 nm wavelength and <3 µm effective axial resolution was used to visualise the microneedle-treated area during insertion and/or following removal of the device, without ...

      Read Full Article
    18. Multispectral in vivo three-dimensional optical coherence tomography of human skin

      Multispectral in vivo three-dimensional optical coherence tomography of human skin

      The capability of optical coherence tomography (OCT) to perform “optical biopsy” of tissues within a depth range of 1 to 2 mm with micron-scale resolution in real time makes it a promising biomedical imaging modality for dermatologic applications. Three high-speed, spectrometer-based frequency-domain OCT systems operating at 800 nm (20,000 A-scans/s), 1060 nm, and 1300 nm (both 47,000 A-scans/s) at comparable signal-to-noise ratio (SNR), SNR roll-off with scanning depth, and transverse resolution (<15 μm) were used to acquire 3-D tomograms of glabrous and hairy human skin in vivo. Images obtained using these three systems were compared in ...

      Read Full Article
    19. Multimodal simultaneous photoacoustic tomography, optical resolution microscopy, and OCT system

      Multimodal simultaneous photoacoustic tomography, optical resolution microscopy, and OCT system

      A novel combined photoacoustic tomography (PAT), optical resolution photoacoustic microscopy (ORPAM) and optical coherence tomography (OCT) instrument has been developed for imaging biological tissues. The system is based on the use of a Fabry-Perot (FP) polymer film ultrasound sensor. This is designed to be transparent to wavelengths between 590nm and 1200nm so that photoacoustic excitation laser pulses in this spectral range can be transmitted through the sensor into the underlying tissue to allow backward mode operation. The dual PAT-ORPAM capability of the system was demonstrated by imaging a tissue phantom composed of 7µm diameter carbon fibres immersed in an ...

      Read Full Article
    20. Real-time in vivo imaging of adult Zebrafish brain using optical coherence tomography

      Real-time in vivo imaging of adult Zebrafish brain using optical coherence tomography

      We report noninvasive imaging of the brain of adult Zebrafish (Danio rerio) using real time optical coherence tomography (OCT) capable of acquiring cross sectional 2D OCT images @ 8 frames/sec. Anatomic features such as telencephalon, tectum opticum, eminentia Granularis and cerebellum were clearly resolved in the OCT images. A 3D model of Zebrafish brain was reconstructed, for the first time to our knowledge, using these 2D OCT images.

      Read Full Article
    1-20 of 20
  1. Categories

    1. Applications:

      Art, Cardiology, Dentistry, Dermatology, Developmental Biology, Gastroenterology, Gynecology, Microscopy, NDE/NDT, Neurology, Oncology, Ophthalmology, Other Non-Medical, Otolaryngology, Pulmonology, Urology
    2. Business News:

      Acquisition, Clinical Trials, Funding, Other Business News, Partnership, Patents
    3. Technology:

      Broadband Sources, Probes, Tunable Sources
    4. Miscellaneous:

      Jobs & Studentships, Student Theses, Textbooks
  2. Topics in the News

    1. (19 articles) Aneesh Alex
    2. (11 articles) Wolfgang Drexler
    3. (8 articles) Medical University of Vienna
    4. (8 articles) Boris Považay
    5. (7 articles) Lehigh University
    6. (7 articles) Chao Zhou
    7. (6 articles) Bernd M. Hofer
    8. (5 articles) Cardiff University
    9. (3 articles) Janarthanan Rasakanthan
    10. (2 articles) Rainer A. Leitgeb
  3. Popular Articles

  4. Picture Gallery

    Real-time in vivo imaging of adult Zebrafish brain using optical coherence tomography Multimodal simultaneous photoacoustic tomography, optical resolution microscopy, and OCT system Multispectral in vivo three-dimensional optical coherence tomography of human skin In Vivo, In Situ Imaging of Microneedle Insertion into the Skin of Human Volunteers Using Optical Coherence Tomography In vivo response of GsdmA3Dfl/+ mice to topically applied anti-psoriatic agents: effects on epidermal thickness, as determined by optical coherence tomography and H&E staining. Multimodal photoacoustic and optical coherence tomography scanner using an all optical detection scheme for 3D morphological skin imaging 3D optical coherence tomography for clinical diagnosis of nonmelanoma skin cancers Three-dimensional calibration targets for optical coherence tomography Feature Of The Week 9/22/13: Lehigh University Researchers Investigate Space-Division Multiplexing for High-Speed Optical Coherence Tomography Optical Coherence Tomography for Brain Imaging and Developmental Biology Retinal Vascular Features in Ocular Blunt Trauma by Optical Coherence Tomography Angiography Non-invasive imaging of a choroidal macrovessel