1. Articles from Stefan Kray

    1-11 of 11
    1. Optical Tomography of MMP Activity Allows a Sensitive Noninvasive Characterization of the Invasiveness and Angiogenesis of SCC Xenografts

      Optical Tomography of MMP Activity Allows a Sensitive Noninvasive Characterization of the Invasiveness and Angiogenesis of SCC Xenografts

      For improved tumor staging and therapy control, imaging biomarkers are of great interest allowing a noninvasive characterization of invasiveness. In squamous epithelial skin and cervix lesions, transition to invasive stages is associated with enhanced matrix metalloproteinase (MMP) activity, increased angiogenesis, and worsened prognosis. Thus, we investigated MMP activity as imaging biomarker of invasiveness and the potential of optical tomography in characterizing the angiogenic and invasive behavior of skin squamous cell carcinoma (SCC) xenografts. MMP activity was measured in vivo in HaCaT-ras A-5RT3 tumors at different angiogenic and invasive stages (onset of angiogenesis, intermediate and highly angiogenic, invasive stage) and after ...

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    2. Polymeric nanoparticles as OCT contrast agents

      Polymeric nanoparticles as OCT contrast agents

      In this study, the optical properties of two nano-sized polymer colloids in optical coherence tomography (OCT) were compared in vitro with respect to their potential use as contrast agents. We used two types of particles: compact hydrophobic spherical polystyrene (PS) particles and soft water-swollen nanogel (NG) particles both with grafted hydrophilic shell, both prepared at two different sizes (PS at 300 and 150 nm, NG at 300 and 200 nm). The OCT backscattering signals of the particles in a vessel-mimicking highly scattering agar/TiO 2 phantom were compared on either number of particles or weight percent. Larger particles and higher ...

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    3. Feature Of The Week 10/9/11: Researchers at RWTH Aachen University Demonstrate Increased Tissue Contrast Using High-Resolution Simultaneous Dual-Band 3D OCT

      Feature Of The Week 10/9/11: Researchers at RWTH Aachen University Demonstrate Increased Tissue Contrast Using High-Resolution Simultaneous Dual-Band 3D OCT
      Classical Optical Coherence Tomography (OCT) systems represent morphological information by displaying the backscattered intensity of the OCT signal. Functional methods like spectroscopic OCT have been developed, extending the contrasting capabilities beyond morphological information. Spectroscopic information arises from wavelength dependent tissue features and has been retrieved by a time-frequency analysis of the OCT signal. However, this method requires high computational effort and is restricted to one wavelength band only.In contrast to a time frequency analysis, detecting in two distinct wavelength bands allows for covering large spectral bandwidths. Contrast enhancement is possible by encoding the spectral differences between both images into ...
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    4. Increased tissue contrast by high-resolution simultaneous dual-band optical coherence tomography in three dimensions

      Increased tissue contrast by high-resolution simultaneous dual-band optical coherence tomography in three dimensions
      Enhanced visualization of tissue contrast and morphological boundaries is demonstrated by analyzing OCT volume data in two distinct wavelength regions. The extension of this so-called simultaneous dual-band method to three dimensions is realized by a custom-built 3D spectral domain OCT system imaging in the 800 und 1200 nm wavelength domain. Color representations of the spectral differences of high resolution OCT volume data significantly simplify the discrimination of different tissue structures beyond the capabilities of cross-sectional spectroscopic OCT approaches.
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    5. Pathogenesis of the dry eye syndrome observed by optical coherence tomography in vitro

      Pathogenesis of the dry eye syndrome observed by optical coherence tomography in vitro
      Three dimensional optical coherence tomography (OCT) is introduced as a valuable tool to analyze the pathogenesis of corneal diseases. Here, OCT in combination with a novel in vitro model for the dry eye syndrome enables an improved understanding of the underlying damaging process of the ocular surface. En-face OCT projections indicate a deep structural damage of the epithelium and anterior stroma by osmotic forces.
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    6. Feature Of The Week 6/6/10: Electronically Controlled Coherent Optical Sampling For Optical Coherence Tomography

      Feature Of The Week 6/6/10: Electronically Controlled Coherent Optical Sampling For Optical Coherence Tomography
      Feature Of The Week 6/6/10: Researchers from the Institute of Semiconductor Electronics at the RWTH Aachen University in Germany have published a variety of interesting papers in OCT. This includes novel work on electronically controlled coherent optical sampling. In optical sampling, a transient waveform under study is gated with time delayed laser pulses to sample this waveform. This gating mechanism can be achieved easily by coherent detection and is commonly performed in low coherence interferometry (LCI) and optical coherence tomography (OCT), where the electric field of the backscattered light of the sample is interfered with time delayed light ...
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    7. Electronically controlled coherent linear optical sampling for optical coherence tomography

      Electronically controlled coherent linear optical sampling for optical coherence tomography
      Electronically controlled coherent linear optical sampling for low coherence interferometry (LCI) and optical coherence tomography (OCT) is demonstrated, using two turn-key commercial mode-locked fiber lasers with synchronized repetition rates. This novel technique prevents repetition rate limitations present in previous implementations based on asynchronous optical sampling. Adjustable scanning ranges and scanning rates are realized within an interferometric setup by full electronic control of the mutual time delay of the two laser pulse trains. We implement this novel linear optical sampling scheme with broad spectral bandwidths for LCI, optical filter characterization and OCT imaging in two and three dimensions.
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    8. Improved contrast in clinical imaging

      Improved contrast in clinical imaging
      Spectral-domain optical coherence tomography performed simultaneously in two distinct wavelength bands permits better diagnosis of tumors. Optical coherence tomography (OCT) is a standard tool for detailed two- and three-dimensional noninvasive analysis of retinal diseases in ophthalmology. It is also a promising research instrument, permitting early tumor diagnosis in skin and bladder tissue. OCT provides high-resolution images of biological tissue using the interference between incident and returning (reflected or backscattered) light1 to obtain structural information that can be used to distinguish between a skin tumor and healthy skin. A particularly important use is to distinguish benign and malignant tumors by means ...
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    9. High-resolution simultaneous dual-band spectral domain optical coherence tomography

      High-resolution simultaneous dual-band spectral domain optical coherence tomography
      A fiber-based spectral domain optical coherence tomography (OCT) system is described, imaging simultaneously at 740 and 1300 nm central wavelengths. Real-time imaging is demonstrated with axial resolutions3um and 5um, respectively. This technique allows for in vivo high-resolution functional OCT imaging withoutstanding spectroscopic contrast.
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    10. Dual femtosecond laser multiheterodyne optical coherence tomography

      Dual femtosecond laser multiheterodyne optical coherence tomography
      A time domain optical coherence tomography (OCT) system without moving parts is described, which is based on multiheterodyning utilizing two mode-locked femtosecond lasers. By synchronizing the two lasers to slightly different repetition rates and coupling to an interferometric OCT setup, we obtain amplitude-modulated beat signals representing the structure of the specimen under investigation. Our system is suitable for biological imaging as well as technical applications. We demonstrate high axial imaging depths of 150 mm with up to 5000 axial scans per second, achieving equivalent path scanning velocities of 750 m/s.
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    11. Simultaneous dual-band ultra-high resolution optical coherence tomography

      Simultaneous dual-band ultra-high resolution optical coherence tomography
      Ultra-high resolution optical coherence tomography (OCT) imaging is demonstrated simultaneously at 840 nm and 1230 nm central wavelength using an off-the-shelf turn-key supercontinuum light source. Spectral filtering of the light source emission results in a double peak spectrum with average powers exceeding 100 mW and bandwidths exceeding 200 nm for each wavelength band. A free-space OCT setup optimized to support both wavelengths in parallel is introduced. OCT imaging of biological tissue ex vivo and in vivo is demonstrated with axial resolutions measured to be < 2 μm and < 4 μm at 840 nm and 1230 nm, respectively. This measuring scheme is ...
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    1-11 of 11
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  2. Topics in the News

    1. (11 articles) RWTH Aachen University
    2. (2 articles) Toptica Photonics
    3. (1 articles) Fianium
    4. (1 articles) Kyoto University Graduate School of Medicine
    5. (1 articles) Carl Zeiss Meditec
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    Dual femtosecond laser multiheterodyne optical coherence tomography High-resolution simultaneous dual-band spectral domain optical coherence tomography Improved contrast in clinical imaging Electronically controlled coherent linear optical sampling for optical coherence tomography Feature Of The Week 6/6/10: Electronically Controlled Coherent Optical Sampling For Optical Coherence Tomography Pathogenesis of the dry eye syndrome observed by optical coherence tomography in vitro Increased tissue contrast by high-resolution simultaneous dual-band optical coherence tomography in three dimensions Simultaneous dual-band ultra-high resolution optical coherence tomography Feature Of The Week 10/9/11: Researchers at RWTH Aachen University Demonstrate Increased Tissue Contrast Using High-Resolution Simultaneous Dual-Band 3D OCT Polymeric nanoparticles as OCT contrast agents Quantification of biomechanical properties of human corneal scar using acoustic radiation force optical coherence elastography Longitudinal changes in complete avascular area assessed using anterior segmental optical coherence tomography angiography in filtering trabeculectomy bleb