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4 results on '"Felix Spöler"'

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

Author

Wa'el Al Rawashdeh, Susanne Arns, Felix Gremse, Josef Ehling, Ruth Knüchel-Clarke, Stefan Kray, Felix Spöler, Fabian Kiessling, and Wiltrud Lederle

Subjects
Neoplasms. Tumors. Oncology. Including cancer and carcinogens, RC254-282
Abstract

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 1 week of sunitinib treatment by fluorescence molecular tomography–microcomputed tomography imaging using an activatable probe. Treatment response was additionally assessed morphologically by optical coherence tomography (OCT). In vivo MMP activity significantly differed between the groups, revealing highest levels in the highly angiogenic, invasive tumors that were confirmed by immunohistochemistry. At the onset of angiogenesis with lowest MMP activity, fibroblasts were detected in the MMP-positive areas, whereas macrophages were absent. Accumulation of both cell types occurred in both invasive groups, again to a significantly higher degree at the most invasive and angiogenic stage. Sunitinib treatment significantly reduced the MMP activity and accumulation of fibroblasts and macrophages and blocked tumor invasion that was additionally visualized by OCT. Human cervical SCCs also showed high MMP activity and a similar stromal composition as the HaCaT xenografts, whereas normal tissue was negative. This study strongly suggests MMP activity as imaging biomarker and demonstrates the high sensitivity of optical tomography in determining tumor invasiveness that can morphologically be supported by OCT.

Published
2014
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2. Electronically controlled coherent linear optical sampling for optical coherence tomography

Author

Stefan Kray, Thomas Hellerer, Heinrich Kurz, and Felix Spöler

Subjects
Transducers, Physics::Optics, Sensitivity and Specificity, law.invention, Optics, Optical coherence tomography, law, Fiber laser, medicine, Fiber Optic Technology, Optical filter, Physics, medicine.diagnostic_test, Amplifiers, Electronic, business.industry, Lasers, Reproducibility of Results, Signal Processing, Computer-Assisted, Equipment Design, Laser, Image Enhancement, Atomic and Molecular Physics, and Optics, Equipment Failure Analysis, Interferometry, Mode-locking, Asynchronous communication, Sample Size, business, Tomography, Optical Coherence, Coherence (physics)
Abstract

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.

Published
2010

3. Dynamic analysis of chemical eye burns using high-resolution optical coherence tomography

Author

Michael Först, Norbert Schrage, Markus Frentz, Heinrich Kurz, and Felix Spöler

Subjects
Materials science, genetic structures, Biomedical Engineering, High resolution, In Vitro Techniques, Sensitivity and Specificity, Light scattering, Biomaterials, Optics, Optical coherence tomography, Cornea, Burns, Chemical, Image Interpretation, Computer-Assisted, medicine, Medical imaging, Animals, medicine.diagnostic_test, business.industry, Reproducibility of Results, Eye irritation, Image Enhancement, eye diseases, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, Ophthalmoscopy, Eye Burns, medicine.anatomical_structure, Initial phase, Temporal resolution, Rabbits, sense organs, business, Algorithms, Biomedical engineering
Abstract

The use of high-resolution optical coherence tomography OCT to visualize penetration kinetics during the initial phase of chemical eye burns is evaluated. The changes in scattering properties and thickness of rabbit cornea ex vivo were monitored after topical application of different corrosives by time-resolved OCT imaging. Eye burn causes changes in the corneal microstructure due to chemical interaction or change in the hydration state as a result of osmotic imbalance. These changes compromise the corneal transparency. The associated increase in light scattering within the cornea is observed with high spatial and temporal resolution. Parameters affecting the severity of pathophysiological damage associated with chemical eye burns like diffusion velocity and depth of penetration are obtained. We demonstrate the potential of high-resolution OCT for the visual- ization and direct noninvasive measurement of specific interaction of chemicals with the eye. This work opens new horizons in clinical evaluation of chemical eye burns, eye irritation testing, and product testing for chemical and pharmacological products. © 2007 Society of

Published
2007
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4. Simultaneous dual-band ultra-high resolution optical coherence tomography

Author

Heinrich Kurz, Stefan Kray, Michael Först, Jörg Bornemann, Patrik Grychtol, Barbara Hermes, and Felix Spöler

Subjects
Point spread function, Materials science, medicine.diagnostic_test, business.industry, Resolution (electron density), Atomic and Molecular Physics, and Optics, Supercontinuum, Wavelength, Optics, Optical coherence tomography, medicine, Multi-band device, business, Image resolution, Preclinical imaging
Abstract

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

Published
2007
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