1. Michael Pircher

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    1. Mentioned In 72 Articles

    2. Detection and Analysis of Hard Exudates by Polarization-Sensitive Optical Coherence Tomography in Patients with Diabetic Maculopathy

      Detection and Analysis of Hard Exudates by Polarization-Sensitive Optical Coherence Tomography in Patients with Diabetic Maculopathy

      Purpose: To image and analyze hard exudates (HE) and their precursors in patients with diabetic macular edema (DME) using polarization sensitive optical coherence tomography (PS-OCT). Methods: Twenty-two eyes of 16 patients with DME were imaged using color fundus photography (CF) and PS-OCT. In PS-OCT, HE were automatically detected based on their distinct polarization-scrambling qualities. CF images were manually graded for the presence of HE by two masked graders and correlated with the corresponding PS-OCT HE maps: corresponding images were overlaid and an identical grid of 128x128 fields was used for correlation of detected HE. Results: In all eyes, HE were ...

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    3. In vitro and in vivo three-dimensional velocity vector measurement by three-beam spectral-domain Doppler optical coherence tomography

      In vitro and in vivo three-dimensional velocity vector measurement by three-beam spectral-domain Doppler optical coherence tomography

      We developed a three-beam Doppler optical coherence tomography (OCT) system that enables measurement of the velocity vector of moving particles in three-dimensions (3-D). The spatial orientation as well as the magnitude of motion can be determined without prior knowledge of the geometry of motion. The system combines three spectral-domain OCT interferometers whose sample beams are focused at the sample by a common focusing lens at three different angles. This provides three spatially independent velocity components simultaneously from which the velocity vector can be reconstructed. We demonstrate the system in a simple test object (rotating disc), a flow phantom, and for ...

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    4. Characterization of Stargardt disease using polarisation-sensitive optical coherence tomography and fundus autofluorescence imaging

      Characterization of Stargardt disease using polarisation-sensitive optical coherence tomography and fundus autofluorescence imaging

      Purpose: To identify disease-specific changes in Stargardt disease (STGD) based on imaging with polarisation-sensitive spectral-domain optical coherence tomography (PS-OCT) and to compare structural changes to those visible on blue light fundus autofluorescence (FAF)imaging. Methods: 28 eyes of 14 patients diagnosed with STGD were imaged using a novel high-speed, large-field PS-OCT system and FAF (Heidelberg Retina Angiograph/Spectralis, Heidelberg Engineering, Germany; excitation 488nm, emission >500nm). The ophthalmoscopic phenotype was classified into 3 groups as suggested by Fishman et al. ABCA4 mutation testing detected 15 STGD alleles, 6 of which harbour novel mutations. Results: STGD phenotype 1 (12 eyes) showed sharply ...

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    5. Imaging Retinal Pigment Epithelial Proliferation Secondary to PASCAL Photocoagulation In Vivo by Polarization-sensitive Optical Coherence Tomography

      Imaging Retinal Pigment Epithelial Proliferation Secondary to PASCAL Photocoagulation In Vivo by Polarization-sensitive Optical Coherence Tomography
      ...ns + Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Vienna, Austria , * Michael Pircher Affiliations + Center for Medical Physics and Biomedical Engineering, Medical University of Vi...
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    6. Retinal polarization-sensitive optical coherence tomography at 1060 nm with 350 kHz A-scan rate using an Fourier domain mode locked laser

      Retinal polarization-sensitive optical coherence tomography at 1060 nm with 350 kHz A-scan rate using an Fourier domain mode locked laser

      We present a novel, high-speed, polarization-sensitive, optical coherence tomography set-up for retinal imaging operating at a central wavelength of 1060 nm which was tested for in vivo imaging in healthy human volunteers. We use the system in combination with a Fourier domain mode locked laser with active spectral shaping which enables the use of forward and backward sweep in order to double the imaging speed without a buffering stage. With this approach and with a custom designed data acquisition system, we show polarization-sensitive imaging with an A-scan rate of 350 kHz. The acquired three-dimensional data sets of healthy human volunteers ...

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    7. Measuring Retinal Nerve Fiber Layer Birefringence, Retardation, and Thickness Using Wide-Field, High-Speed Polarization Sensitive Spectral Domain OCT

      Measuring Retinal Nerve Fiber Layer Birefringence, Retardation, and Thickness Using Wide-Field, High-Speed Polarization Sensitive Spectral Domain OCT
      ... and Thickness Using Wide-Field, High-Speed Polarization Sensitive Spectral Domain OCT 1. Stefan Zotter^1, 2. Michael Pircher^1, 3. Erich Götzinger^1, 4. Teresa Torzicky^1, 5. Hirofumi Yoshida^2, 6. Futoshi Hirose^2, 7. ...
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    8. Lesion Size Detection in Geographic Atrophy by Polarization-sensitive Optical Coherence Tomography and Correlation to Conventional Imaging Techniques

      Lesion Size Detection in Geographic Atrophy by Polarization-sensitive Optical Coherence Tomography and Correlation to Conventional Imaging Techniques

      Purpose: To investigate the reproducibility of automated lesion size detection in patients with geographic atrophy (GA) using polarization-sensitive spectral domain-OCT (PS-OCT) and to compare findings with scanning laser ophthalmoscopy (SLO), fundus autofluorescence (FAF), and intensity based SD-OCT. Methods: 29 eyes of 22 patients with GA were examined by PS-OCT, selectively identifying the retinal pigment epithelium (RPE). A novel segmentation algorithm was applied, automatically detecting and quantifying areas of RPE atrophy. The reproducibility of the algorithm was assessed and lesion sizes were correlated with manually delineated SLO, FAF and intensity based SD-OCT images to validate the clinical applicability of PS-OCT in ...

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    9. High-speed polarization sensitive optical coherence tomography scan engine based on Fourier domain mode locked laser

      High-speed polarization sensitive optical coherence tomography scan engine based on Fourier domain mode locked laser

      We report on a new swept source polarization sensitive optical coherence tomography scan engine that is based on polarization maintaining (PM) fiber technology. The light source is a Fourier domain mode locked laser with a PM cavity that operates in the 1300 nm wavelength regime. It is equipped with a PM buffer stage that doubles the fundamental sweep frequency of 54.5 kHz. The fiberization allows coupling of the scan engine to different delivery probes. In a first demonstration, we use the system for imaging human skin at an A-scan rate of 109 kHz. The system illuminates the sample with ...

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    10. Large-field high-speed polarization sensitive spectral domain OCT and its applications in ophthalmology

      Large-field high-speed polarization sensitive spectral domain OCT and its applications in ophthalmology
      We present a novel spectral domain polarization sensitive OCT system (PS-OCT) that operates at an A-scan rate of 70 kHz and supports scan angles of up to 40° × 40°. The high-speed imaging allows the acquisition of up to 1024 × 250 A-scans per 3D scan, which, together with the large field of view, considerably increases the informative value of the images. To demonstrate the excellent performance of the new PS-OCT system, we imaged several healthy volunteers and patients with various diseases such as glaucoma, AMD, Stargardt’s disease, and albinism. The results are compared with clinically established methods such as scanning ...
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    11. Polarization sensitive optical coherence tomography of melanin provides intrinsic contrast based on depolarization

      Polarization sensitive optical coherence tomography of melanin provides intrinsic contrast based on depolarization

      Polarization sensitive optical coherence tomography (PS-OCT) is a functional extension of OCT. In addition to imaging based on tissue reflectivity, PS-OCT also enables depth-resolved mapping of sample polarization properties such as phase-retardation, birefringent axis orientation, Stokes vectors, and degree of polarization uniformity (DOPU). In this study, PS-OCT was used to investigate the polarization properties of melanin. In-vitro measurements in samples with varying melanin concentrations revealed polarization scrambling, i.e. depolarization of backscattered light. Polarization scrambling in the PS-OCT images was more pronounced for higher melanin concentrations and correlated with the concentration of the melanin granules in the phantoms. Moreover, in-vivo ...

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    12. High-speed polarization-sensitive OCT at 1060 nm using a Fourier domain mode-locked swept source

      High-speed polarization-sensitive OCT at 1060 nm using a Fourier domain mode-locked swept source

      Optical coherence tomography (OCT) in the 1060nm range is interesting for in vivo imaging of the human posterior eye segment (retina, choroid, sclera), as it permits a long penetration depth. Complementary to structural images, polarization-sensitive OCT (PS-OCT) images visualize birefringent, polarization-maintaining or depolarizing areas within the sample. This information can be used to distinguish retinal layers and structures with different polarization properties. High imaging speed is crucial for imaging ocular structures in vivo in order to minimize motion artifacts while acquiring sufficiently large datasets. Here, we demonstrate PS-OCT imaging at 350 kHz A-scan rate using a two-channel PS-OCT system in ...

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    13. Feature Of The Week 4/29/12: Medical University of Vienna Demonstrates Automated Measurement of Choroidal Thickness in the Human Eye by PS-OCT

      Feature Of The Week 4/29/12: Medical University of Vienna Demonstrates Automated Measurement of Choroidal Thickness in the Human Eye by PS-OCT

      Researchers at the Medical University of Vienna have a long history of outstanding contributions to the field of Optical Coherence Tomography dating back 25 years.  This week work by Dr. Hitzenberger, one of the pioneers of the field, and his colleagues is featured demonstrating automated measurement of choroidal thickness in the human eye by polarization sensitive optical coherence tomography. Below is a summary of their work.Imaging of retinal layers and quantitative measurements of their thickness are among the most important applications of OCT. E.g., the total retinal thickness is an important quantity for diagnosis of diabetic retinopathy, the ...

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    14. High-Speed Retinal Imaging with Polarization-Sensitive OCT at 1040 nm

      High-Speed Retinal Imaging with Polarization-Sensitive OCT at 1040 nm

      Purpose. To demonstrate the ability of a new high-speed polarization-sensitive optical coherence tomography (PS-OCT) system for retinal imaging at 1040 nm. Methods. A new polarization-sensitive swept source OCT system in the 1 [mu]m wavelength range is used to image the retina of healthy volunteers. The instrument is operated at an A-scan rate of 100 kHz which is about three times faster than previously reported PS-OCT instruments in this wavelength region. The increased imaging speed can be used to record densely sampled volumes of the retina. Moreover, it enables averaging of several B-scans recorded at the same location to obtain ...

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  2. About Michael Pircher

    Michael Pircher

    Michael Pircher graduated from the Experimental Physics Department of the University of Technology of Graz, Austria in 2000. In 2003 he finished his PhD at the University of Technology of Vienna. From 2003 to 2006 he worked as a Postdoc at the Center for Biomedical Engineering and Physics of the Medical University of Vienna. From 2006 to 2012 he was working as an Assistant Professor at the Center for Medical Physics and Biomedical Engineering of the Medical University of Vienna where he gained his Habilitation in 2008. Currently he is Associate Professor and faculty member of the same department. His scientific interest lies in retinal imaging, adaptive optics, new contrast techniques in optical coherence tomography, coherence microscopy