2018
|
Gianni Borghesan; Mouloud Ourak; Eva Lankenau; Gereon Hüttmann; Hinnerk Schulz-Hildebrant; Koen Willekens; Peter Stalmans; Dominiek Reynaerts; Emmanuel Vander Poorten Single Scan OCT-based Retina Detection for Robot-assisted Retinal Vein Cannulation Journal Article In: Journal of Medical Robotics Research, vol. 3, no. 02, pp. 184005, 2018. @article{borghesan2018single,
title = {Single Scan OCT-based Retina Detection for Robot-assisted Retinal Vein Cannulation},
author = {Gianni Borghesan and Mouloud Ourak and Eva Lankenau and Gereon H\"{u}ttmann and Hinnerk Schulz-Hildebrant and Koen Willekens and Peter Stalmans and Dominiek Reynaerts and Emmanuel Vander Poorten},
editor = {World Scientific},
url = {https://www.worldscientific.com/doi/abs/10.1142/S2424905X18400056},
doi = {10.1142/S2424905X18400056},
year = {2018},
date = {2018-02-12},
journal = {Journal of Medical Robotics Research},
volume = {3},
number = {02},
pages = {184005},
abstract = {Vitreoretinal surgery concerns a set of particularly demanding minimal invasive micro-surgical interventions at the retina. Micro-surgeons are targeting sub-millimeter-sized structures here. Tiny vessels or wafer-thin membranes are to be cannulated or need to be peeled off. The greatest care is to be displayed not to damage these fragile structures or to inadvertently injure the underlying retina. Damage to the latter is mostly irreparable and might cause permanent loss of vision. Despite the availability over excellent stereo microscopes, wide-angle lenses and powerful light source visualization remains a problem. Especially, the limited depth perception is still perceived as a major bottle-neck whereas efforts have been conducted to integrate sensing capability in today’s state-of-the-art instruments, so far, little effort has been paid to process the obtained sensor data and turns this into a reliable source of information upon which robot assistive guidance schemes could be endowed upon. This paper proposes a number of processing techniques tailored to Optical Coherence Tomography (OCT) measurements. The first results of the proposed algorithms show that it is feasible to extract good and reliable distance estimates from this otherwise rather noisy signal and from a fairly limited dataset. The used data are the so-called A-scans. These are OCT measurements consisting of a single-line image that could be captured by an instrument-mounted fiber through which the OCT signal passes back-and-forth. However, in this work, we perform a pilot study whereby the employed A-scans are extracted from B-scans that are captured by a microscope-mounted OCT scanner, rather than obtained from a probe. The performance of a first embodiment of the algorithm that is based on an Unscented Kalman Filter (UKF) is compared to the performance of a second embodiment that relies on a Particle Filter (PF), focusing on the issues in filter initialization and the tracking quality. Finally, results of UKF and PF executions on a validation dataset are presented.
Read More: https://www.worldscientific.com/doi/abs/10.1142/S2424905X18400056},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Vitreoretinal surgery concerns a set of particularly demanding minimal invasive micro-surgical interventions at the retina. Micro-surgeons are targeting sub-millimeter-sized structures here. Tiny vessels or wafer-thin membranes are to be cannulated or need to be peeled off. The greatest care is to be displayed not to damage these fragile structures or to inadvertently injure the underlying retina. Damage to the latter is mostly irreparable and might cause permanent loss of vision. Despite the availability over excellent stereo microscopes, wide-angle lenses and powerful light source visualization remains a problem. Especially, the limited depth perception is still perceived as a major bottle-neck whereas efforts have been conducted to integrate sensing capability in today’s state-of-the-art instruments, so far, little effort has been paid to process the obtained sensor data and turns this into a reliable source of information upon which robot assistive guidance schemes could be endowed upon. This paper proposes a number of processing techniques tailored to Optical Coherence Tomography (OCT) measurements. The first results of the proposed algorithms show that it is feasible to extract good and reliable distance estimates from this otherwise rather noisy signal and from a fairly limited dataset. The used data are the so-called A-scans. These are OCT measurements consisting of a single-line image that could be captured by an instrument-mounted fiber through which the OCT signal passes back-and-forth. However, in this work, we perform a pilot study whereby the employed A-scans are extracted from B-scans that are captured by a microscope-mounted OCT scanner, rather than obtained from a probe. The performance of a first embodiment of the algorithm that is based on an Unscented Kalman Filter (UKF) is compared to the performance of a second embodiment that relies on a Particle Filter (PF), focusing on the issues in filter initialization and the tracking quality. Finally, results of UKF and PF executions on a validation dataset are presented.
Read More: https://www.worldscientific.com/doi/abs/10.1142/S2424905X18400056 |
Hinnerk Schulz-Hildebrandt; Mario Pieper; Charlotte Stehmar; Martin Ahrens; Christian Idel; Barbara Wollenberg; Peter König; Gereon Hüttmann Novel endoscope with increased depth of field for imaging human nasal tissue by microscopic optical coherence tomography Journal Article In: Biomedical Optics Express, vol. 9, no. 2, pp. 636-647, 2018, ISBN: 10.1364/BOE.9.000636. @article{schulz2018novel,
title = {Novel endoscope with increased depth of field for imaging human nasal tissue by microscopic optical coherence tomography},
author = {Hinnerk Schulz-Hildebrandt and Mario Pieper and Charlotte Stehmar and Martin Ahrens and Christian Idel and Barbara Wollenberg and Peter K\"{o}nig and Gereon H\"{u}ttmann},
editor = {Optical Society of America},
url = {https://www.osapublishing.org/abstract.cfm?URI=boe-9-2-636
https://www.osapublishing.org/boe/viewmedia.cfm?uri=boe-9-2-636\&seq=0},
doi = {10.1364/BOE.9.000636},
isbn = {10.1364/BOE.9.000636},
year = {2018},
date = {2018-01-16},
journal = {Biomedical Optics Express},
volume = {9},
number = {2},
pages = {636-647},
abstract = {Intravital microscopy (IVM) offers the opportunity to visualize static and dynamic changes of tissue on a cellular level. It is a valuable tool in research and may considerably improve clinical diagnosis. In contrast to confocal and non-linear microscopy, optical coherence tomography (OCT) with microscopic resolution (mOCT) provides intrinsically cross-sectional imaging. Changing focus position is not needed, which simplifies especially endoscopic imaging. For in-vivo imaging, here we are presenting endo-microscopic OCT (emOCT). A graded-index-lens (GRIN) based 2.75 mm outer diameter rigid endoscope is providing 1.5 \textendash 2 μm nearly isotropic resolution over an extended field of depth. Spherical and chromatic aberrations are used to elongate the focus length. Simulation of the OCT image formation, suggests overall a better image quality in this range compared to a focused Gaussian beam. Total imaging depth at a reduced sensitivity and lateral resolution is more than 200 μm. Using a frame rate of 80 Hz cross-sectional images of concha nasalis were demonstrated in humans, which could resolve cilial motion, cellular structures of the epithelium, vessels and blood cells. Mucus transport velocity was determined successfully. The endoscope may be used for diagnosis and treatment control of different lung diseases like cystic fibrosis or primary ciliary dyskinesia, which manifest already at the nasal mucosa.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Intravital microscopy (IVM) offers the opportunity to visualize static and dynamic changes of tissue on a cellular level. It is a valuable tool in research and may considerably improve clinical diagnosis. In contrast to confocal and non-linear microscopy, optical coherence tomography (OCT) with microscopic resolution (mOCT) provides intrinsically cross-sectional imaging. Changing focus position is not needed, which simplifies especially endoscopic imaging. For in-vivo imaging, here we are presenting endo-microscopic OCT (emOCT). A graded-index-lens (GRIN) based 2.75 mm outer diameter rigid endoscope is providing 1.5 – 2 μm nearly isotropic resolution over an extended field of depth. Spherical and chromatic aberrations are used to elongate the focus length. Simulation of the OCT image formation, suggests overall a better image quality in this range compared to a focused Gaussian beam. Total imaging depth at a reduced sensitivity and lateral resolution is more than 200 μm. Using a frame rate of 80 Hz cross-sectional images of concha nasalis were demonstrated in humans, which could resolve cilial motion, cellular structures of the epithelium, vessels and blood cells. Mucus transport velocity was determined successfully. The endoscope may be used for diagnosis and treatment control of different lung diseases like cystic fibrosis or primary ciliary dyskinesia, which manifest already at the nasal mucosa. |
2017
|
Jens Horstmann; Hinnerk Schulz-Hildebrandt; Felix Bock; Sebastian Siebelmann; Eva Lankenau; Gereon Hüttmann; Philipp Steven; Claus Cursiefen Label-Free In Vivo Imaging of Corneal Lymphatic Vessels Using Microscopic Optical Coherence Tomography Journal Article In: Investigative Ophthalmology & Visual Science, vol. 58, no. 13, pp. 5880-5886, 2017, ISBN: 1552-5783. @article{Horstmann2017,
title = {Label-Free In Vivo Imaging of Corneal Lymphatic Vessels Using Microscopic Optical Coherence Tomography},
author = {Jens Horstmann and Hinnerk Schulz-Hildebrandt and Felix Bock and Sebastian Siebelmann and Eva Lankenau and Gereon H\"{u}ttmann and Philipp Steven and Claus Cursiefen},
editor = {The Association Research for in Vision and Ophthalmology},
url = {http://iovs.arvojournals.org/article.aspx?articleid=2664271},
doi = {10.1167/iovs.17-22286},
isbn = {1552-5783},
year = {2017},
date = {2017-12-25},
journal = {Investigative Ophthalmology \& Visual Science},
volume = {58},
number = {13},
pages = {5880-5886},
abstract = {Purpose: Corneal neovascularization, in particular lymphangiogenesis, is a limiting factor in corneal transplant survival. Novel treatment approaches focus on (selective) inhibition and regression of lymphatic vessels. Imaging clinically invisible corneal lymphatic vessels is a prerequisite for these strategies. Using a murine model, this study investigates whether corneal lymphatic vessels can be imaged using microscopic optical coherence tomography (mOCT).
Methods: Corneal neovascularization was induced by intrastromal placement of 11.0 nylon sutures in one eye of BALB/c mice. After 2 weeks, cross-sectional images and volumes of the corneas with a 0.5 mm lateral and axial field of view were acquired using a custom-built mOCT system enabling a resolution of 1 μm at a B-scan rate of 165/s. Three of the six animals received an additional intrastromal injection of India ink 24 hours before the measurement to stain the corneal lymphatic system in vivo. Immunohistochemistry using CD31 and LYVE-1 was used to validate the mOCT findings.
Results: Using mOCT, lymphatic vessels were visible as dark vessel-like structures with the lumen lacking a hyperreflective wall and mostly lacking cells. However, individual, slowly moving particles, which most likely are immune cells, occasionally could be observed inside the lumen. In lymphatic vessels of ink-stained corneas, hyperreflection and shadowing underneath was observed. Ink-filled lymphatic vessels were colocalized in consecutive corneal flat mounts of the same specimen.
Conclusions: Corneal lymphatic vessels can be imaged using mOCT. This novel approach opens new options for noninvasive clinical imaging of corneal lymphatic vessels for diagnostic and therapeutic indications.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Purpose: Corneal neovascularization, in particular lymphangiogenesis, is a limiting factor in corneal transplant survival. Novel treatment approaches focus on (selective) inhibition and regression of lymphatic vessels. Imaging clinically invisible corneal lymphatic vessels is a prerequisite for these strategies. Using a murine model, this study investigates whether corneal lymphatic vessels can be imaged using microscopic optical coherence tomography (mOCT).
Methods: Corneal neovascularization was induced by intrastromal placement of 11.0 nylon sutures in one eye of BALB/c mice. After 2 weeks, cross-sectional images and volumes of the corneas with a 0.5 mm lateral and axial field of view were acquired using a custom-built mOCT system enabling a resolution of 1 μm at a B-scan rate of 165/s. Three of the six animals received an additional intrastromal injection of India ink 24 hours before the measurement to stain the corneal lymphatic system in vivo. Immunohistochemistry using CD31 and LYVE-1 was used to validate the mOCT findings.
Results: Using mOCT, lymphatic vessels were visible as dark vessel-like structures with the lumen lacking a hyperreflective wall and mostly lacking cells. However, individual, slowly moving particles, which most likely are immune cells, occasionally could be observed inside the lumen. In lymphatic vessels of ink-stained corneas, hyperreflection and shadowing underneath was observed. Ink-filled lymphatic vessels were colocalized in consecutive corneal flat mounts of the same specimen.
Conclusions: Corneal lymphatic vessels can be imaged using mOCT. This novel approach opens new options for noninvasive clinical imaging of corneal lymphatic vessels for diagnostic and therapeutic indications. |
Jens Horstmann; Sebastian Siebelmann; Hinnerk Schulz-Hildebrandt; I Glasunow; A Schadschneider; Gereon Hüttmann Understanding OCT – Part 2: State of the Practice Journal Article In: Klinische Monatsblatter fur Augenheilkunde, vol. 234, no. 2, pp. 233-247, 2017. @article{Horstmann2017c,
title = {Understanding OCT \textendash Part 2: State of the Practice},
author = {Jens Horstmann and Sebastian Siebelmann and Hinnerk Schulz-Hildebrandt and I Glasunow and A Schadschneider and Gereon H\"{u}ttmann},
editor = {Thieme},
doi = {10.1055/s-0033-1358249},
year = {2017},
date = {2017-11-21},
journal = {Klinische Monatsblatter fur Augenheilkunde},
volume = {234},
number = {2},
pages = {233-247},
abstract = {Den Schwerpunkt dieses Artikels bildet die Vermittlung praktischen Wissens rund um die optische Koh\"{a}renztomografie (OCT). W\"{a}hrend in Teil 1 [1] die physikalischen Grundlagen vorgestellt wurden, werden hier praktische Aspekte f\"{u}r den Anwender erl\"{a}utert, unabh\"{a}ngig vom verwendeten Ger\"{a}tetyp oder Hersteller.
Grunds\"{a}tzliche Parameter und Einstellm\"{o}glichkeiten werden vorgestellt. Es wird hinterfragt, was ein OCT-Bild eigentlich zeigt und wann bei der Interpretation und Auswertung Vorsicht geboten ist. Typische Artefakte sowie deren Ursachen und M\"{o}glichkeiten der Vermeidung werden diskutiert. Zuletzt wird eine \"{U}bersicht \"{u}ber aktuelle Anwendungsfelder der OCT in der Augenheilkunde gegeben},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Den Schwerpunkt dieses Artikels bildet die Vermittlung praktischen Wissens rund um die optische Kohärenztomografie (OCT). Während in Teil 1 [1] die physikalischen Grundlagen vorgestellt wurden, werden hier praktische Aspekte für den Anwender erläutert, unabhängig vom verwendeten Gerätetyp oder Hersteller.
Grundsätzliche Parameter und Einstellmöglichkeiten werden vorgestellt. Es wird hinterfragt, was ein OCT-Bild eigentlich zeigt und wann bei der Interpretation und Auswertung Vorsicht geboten ist. Typische Artefakte sowie deren Ursachen und Möglichkeiten der Vermeidung werden diskutiert. Zuletzt wird eine Übersicht über aktuelle Anwendungsfelder der OCT in der Augenheilkunde gegeben |
Jens Horstmann; Sebastian Siebelmann; Hinnerk Schulz-Hildebrandt; I Glasunow; A Schadschneider; Gereon Hüttmann Understanding OCT-Part 1: Basic Knowledge Journal Article In: Klinische Monatsblatter fur Augenheilkunde, vol. 234, no. 1, pp. 131-143, 2017. @article{Horstmann2017b,
title = {Understanding OCT-Part 1: Basic Knowledge},
author = {Jens Horstmann and Sebastian Siebelmann and Hinnerk Schulz-Hildebrandt and I Glasunow and A Schadschneider and Gereon H\"{u}ttmann},
doi = {10.1055/s-0042-119126},
year = {2017},
date = {2017-11-02},
journal = {Klinische Monatsblatter fur Augenheilkunde},
volume = {234},
number = {1},
pages = {131-143},
abstract = {Die optische Koh\"{a}renztomografie (OCT) ist ein in vielen Bereichen der Augenheilkunde etabliertes Bildgebungsverfahren. Im 1. Teil zum Thema OCT werden technisch-physikalische Grundlagen zum Verst\"{a}ndnis vermittelt. Die prinzipielle Arbeitsweise der OCT wird erl\"{a}utert. Die zugrundeliegende Licht-Gewebe-Wechselwirkung sowie die OCT-Messtechnik werden beschrieben und verschiedene OCT-Verfahren vorgestellt. Komplexe physikalische Vorg\"{a}nge werden dabei anschaulich dargestellt und Formeln weitgehend vermieden. Hintergrundboxen laden zu einem tieferen Verst\"{a}ndnis ein. Ziel dieses Artikels ist ein Grundverst\"{a}ndnis der Methode zu vermitteln, das helfen soll, die OCT und ihre Aufnahmen zu verstehen. Die praktische Anwendung der OCT ist in Teil 2 [1] dargestellt.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Die optische Kohärenztomografie (OCT) ist ein in vielen Bereichen der Augenheilkunde etabliertes Bildgebungsverfahren. Im 1. Teil zum Thema OCT werden technisch-physikalische Grundlagen zum Verständnis vermittelt. Die prinzipielle Arbeitsweise der OCT wird erläutert. Die zugrundeliegende Licht-Gewebe-Wechselwirkung sowie die OCT-Messtechnik werden beschrieben und verschiedene OCT-Verfahren vorgestellt. Komplexe physikalische Vorgänge werden dabei anschaulich dargestellt und Formeln weitgehend vermieden. Hintergrundboxen laden zu einem tieferen Verständnis ein. Ziel dieses Artikels ist ein Grundverständnis der Methode zu vermitteln, das helfen soll, die OCT und ihre Aufnahmen zu verstehen. Die praktische Anwendung der OCT ist in Teil 2 [1] dargestellt. |
Sarah Latus; Christoph Otte; Matthias Schlüter; Josua Rehra; Kevin Bizon; Hinnerk Schulz-Hildebrandt; Thore Saathoff; Gereon Hüttmann; Alexander Schlaefer An Approach for Needle Based Optical Coherence Elastography Measurements Conference Medical Image Computing and Computer-Assisted Intervention − MICCAI 2017, vol. 10434, Springer 2017, ISBN: 978-3-319-66185-8. @conference{Latus2017,
title = {An Approach for Needle Based Optical Coherence Elastography Measurements},
author = {Sarah Latus and Christoph Otte and Matthias Schl\"{u}ter and Josua Rehra and Kevin Bizon and Hinnerk Schulz-Hildebrandt and Thore Saathoff and Gereon H\"{u}ttmann and Alexander Schlaefer},
editor = {Springer International Publishing},
url = {https://link.springer.com/chapter/10.1007/978-3-319-66185-8_74},
doi = {https://doi.org/10.1007/978-3-319-66185-8_74},
isbn = {978-3-319-66185-8},
year = {2017},
date = {2017-09-01},
booktitle = {Medical Image Computing and Computer-Assisted Intervention − MICCAI 2017},
volume = {10434},
pages = {655--663},
organization = {Springer},
abstract = {© Springer International Publishing AG 2017.
While navigation and interventional guidance are typically based on image data, the images do not necessarily reflect mechanical tissue properties. Optical coherence elastography (OCE) presents a modality with high sensitivity and very high spatial and temporal resolution. However, OCE has a limited field of view of only 2\textendash5 mm depth. We present a side-facing needle probe to image externally induced shear waves from within soft tissue. A first method of quantitative needle-based OCE is provided. Using a time of flight setup, we establish the shear wave velocity and estimate the tissue elasticity. For comparison, an external scan head is used for imaging. Results for four different phantoms indicate a good agreement between the shear wave velocities estimated from the needle probe at different depths and the scan head. The velocities ranging from 0.9\textendash3.4 m/s agree with the expected values, illustrating that tissue elasticity estimates from within needle probes are feasible.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
© Springer International Publishing AG 2017.
While navigation and interventional guidance are typically based on image data, the images do not necessarily reflect mechanical tissue properties. Optical coherence elastography (OCE) presents a modality with high sensitivity and very high spatial and temporal resolution. However, OCE has a limited field of view of only 2–5 mm depth. We present a side-facing needle probe to image externally induced shear waves from within soft tissue. A first method of quantitative needle-based OCE is provided. Using a time of flight setup, we establish the shear wave velocity and estimate the tissue elasticity. For comparison, an external scan head is used for imaging. Results for four different phantoms indicate a good agreement between the shear wave velocities estimated from the needle probe at different depths and the scan head. The velocities ranging from 0.9–3.4 m/s agree with the expected values, illustrating that tissue elasticity estimates from within needle probes are feasible. |
Gianni Borghesan; Mouloud Ourak; Eva Lankenau; Richard Neffin; Peter Koch; Hinnerk Schulz-Hildebrandt; Koen Willekens; Peter Stalmans; Dominiek Reynaerts; Emmanuel Vander Poorten Probabilistic Principal Component Analysis and Particle Filtering for real-time retina detection from a single-fiber OCT Conference Proceedings of the 7th Joint Workshop on New Technologies for Computer/Robot Assisted Surgery, 2017. @conference{Borghesan2017,
title = {Probabilistic Principal Component Analysis and Particle Filtering for real-time retina detection from a single-fiber OCT},
author = {Gianni Borghesan and Mouloud Ourak and Eva Lankenau and Richard Neffin and Peter Koch and Hinnerk Schulz-Hildebrandt and Koen Willekens and Peter Stalmans and Dominiek Reynaerts and Emmanuel Vander Poorten},
year = {2017},
date = {2017-06-02},
booktitle = {Proceedings of the 7th Joint Workshop on New Technologies for Computer/Robot Assisted Surgery},
abstract = {Vitreo-retinal surgery concerns a set of particularly demanding micro-surgical interventions that take place at the back of the eye. Examples of such procedures are retinal vein cannulation (where the surgeon aims to insert a needle in a vein of the size of human hairs) and epiretinal membrane peeling (where a detached membrane must be removed from the retina). As severe retinal damage can be caused by undesired collisions, good instrument to retina distance perception would be very useful. We propose to use an OCT-fiber instrumented tool, and purposefully designed algorithms to interpret the measurements and extract a reliable real-time distance estimate. This abstract describes the progress that was made and includes a test conducted with a robotic platform on a synthetic eye mockup.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Vitreo-retinal surgery concerns a set of particularly demanding micro-surgical interventions that take place at the back of the eye. Examples of such procedures are retinal vein cannulation (where the surgeon aims to insert a needle in a vein of the size of human hairs) and epiretinal membrane peeling (where a detached membrane must be removed from the retina). As severe retinal damage can be caused by undesired collisions, good instrument to retina distance perception would be very useful. We propose to use an OCT-fiber instrumented tool, and purposefully designed algorithms to interpret the measurements and extract a reliable real-time distance estimate. This abstract describes the progress that was made and includes a test conducted with a robotic platform on a synthetic eye mockup. |
Malte Casper; Hinnerk Schulz-Hildebrandt; Michael Evers; Cuc Nguyen; Reginald Birngruber; Gereon Hüttmann; Dieter Manstein Imaging cold-induced vasodynamic behaviour in skin using OCT for microangiography (Conference Presentation) Conference Proceedings Volume 10037, Photonics in Dermatology and Plastic Surgery, vol. 10037OS, 2017. @conference{Casper2017,
title = {Imaging cold-induced vasodynamic behaviour in skin using OCT for microangiography (Conference Presentation)},
author = {Malte Casper and Hinnerk Schulz-Hildebrandt and Michael Evers and Cuc Nguyen and Reginald Birngruber and Gereon H\"{u}ttmann and Dieter Manstein},
editor = {Spie},
doi = {doi: 10.1117/12.2251485},
year = {2017},
date = {2017-04-19},
booktitle = {Proceedings Volume 10037, Photonics in Dermatology and Plastic Surgery},
volume = {10037OS},
abstract = {In dermatology the reflexes of vasoconstriction and vasodilation are known as important mechanisms of thermoregulation of the inner body. Imaging the physiology of microvasculature of the skin with high spatial resolution in three dimensions while reacting to changes in temperature is crucial for understanding the complex processes of vasodynamics, which result in constriction and dilation of vessels. However, previous studies using Laser-Doppler flowmetry and -imaging could not provide reliable angiographic images which allow to quantify changes in blood vessel diameter. Here, we report a different approach for angiographic imaging of microvasculature of a anaesthetized rodent model using speckle variance optical coherence tomography (svOCT) during and after localized cooling. Therefore a commercial OCT with a center wavelength of 1.3 μm and a spatial resolution of 13µm was used in combination with a custom built cooling device to image such reflexes at the mouse ear pinna and dorsal skinfold. Cooling was applied in steps of 2−5◦ C starting at the baseline temperature of 27◦ C down to −10◦ C. To our surprise and in contrast to the general opinion in literature, we were able to observe that the majority of vessels with a diameter larger than 20 μm maintain perfused with a constant diameter when the tissue is cooled from baseline to subzero temperatures. However, vasoconstriction was observed very rarely and only in veins, which led to their occlusion. The results of this experiment lead us to reconsider essential aspects of previous understanding of temperature-induced vasodynamics in cutaneous microvasculature.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
In dermatology the reflexes of vasoconstriction and vasodilation are known as important mechanisms of thermoregulation of the inner body. Imaging the physiology of microvasculature of the skin with high spatial resolution in three dimensions while reacting to changes in temperature is crucial for understanding the complex processes of vasodynamics, which result in constriction and dilation of vessels. However, previous studies using Laser-Doppler flowmetry and -imaging could not provide reliable angiographic images which allow to quantify changes in blood vessel diameter. Here, we report a different approach for angiographic imaging of microvasculature of a anaesthetized rodent model using speckle variance optical coherence tomography (svOCT) during and after localized cooling. Therefore a commercial OCT with a center wavelength of 1.3 μm and a spatial resolution of 13µm was used in combination with a custom built cooling device to image such reflexes at the mouse ear pinna and dorsal skinfold. Cooling was applied in steps of 2−5◦ C starting at the baseline temperature of 27◦ C down to −10◦ C. To our surprise and in contrast to the general opinion in literature, we were able to observe that the majority of vessels with a diameter larger than 20 μm maintain perfused with a constant diameter when the tissue is cooled from baseline to subzero temperatures. However, vasoconstriction was observed very rarely and only in veins, which led to their occlusion. The results of this experiment lead us to reconsider essential aspects of previous understanding of temperature-induced vasodynamics in cutaneous microvasculature. |
Hinnerk Schulz-Hildebrandt; Benjamin Sauer; Fred Reinholz; Mario Pieper; Markus Mall; Peter König; Gereon Huettmann Improving imaging of the air-liquid interface in living mice by aberration-corrected optical coherence tomography (mOCT) (Conference Presentation) Conference Proceedings Volume 10041, Optical Techniques in Pulmonary Medicine II, vol. 1004105, 2017. @conference{Schulz-Hildebrandt2017,
title = {Improving imaging of the air-liquid interface in living mice by aberration-corrected optical coherence tomography (mOCT) (Conference Presentation)},
author = {Hinnerk Schulz-Hildebrandt and Benjamin Sauer and Fred Reinholz and Mario Pieper and Markus Mall and Peter K\"{o}nig and Gereon Huettmann},
doi = {doi: 10.1117/12.2252558},
year = {2017},
date = {2017-04-17},
booktitle = {Proceedings Volume 10041, Optical Techniques in Pulmonary Medicine II},
volume = {1004105},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
|
2016
|
Hinnerk Schulz-Hildebrandt; Mario Pieper; J Kasper; Nadine Traulsen; Markus Mall; Peter König; Gereon Hüttmann Towards automated evaluation of mucus transport measured by microscopic OCT (mOCT) during hypertonic saline treatment of Cystic Fibrosis Conference Pneumologie, vol. 70, no. 07, 2016. @conference{Schulz-Hildebrandt2016,
title = {Towards automated evaluation of mucus transport measured by microscopic OCT (mOCT) during hypertonic saline treatment of Cystic Fibrosis},
author = {Hinnerk Schulz-Hildebrandt and Mario Pieper and J Kasper and Nadine Traulsen and Markus Mall and Peter K\"{o}nig and Gereon H\"{u}ttmann},
url = {http://www.schulz-hildebrandt.com/wp-content/uploads/2018/04/SchulzHildebrandt2016.jpg},
doi = {10.1055/s-0036-1584651},
year = {2016},
date = {2016-07-01},
booktitle = {Pneumologie},
volume = {70},
number = {07},
pages = {48},
abstract = {Effective mucus transport in the airways is essential for infection defense. Malfunction caused by diseases like cystic fibrosis (CF) can result in severe and even life threatening complications. Time resolved imaging of mucus transport in vivo is essential to get mechanistic insight in factors influencing the transport and for developing and testing therapeutic interventions to increase mucus transport.
Microscopic OCT (mOCT) was used successfully to image mucus transport in trachea of spontaneous breathing mice. Image series over more than 2 hours containing 35,000 frames were captured in wild type (WT) and βENaC overexpressing mice, which served as a model for CF. In order to evaluate these large amount of data an automatic quantitative evaluation is need. This has to include an efficient correction of tissue motion and an automatic identification and rejection of non-evaluable frames.
In this study we compared two algorithms for motion correction. A pairwise correlation of the different frame for calculation of the motion vector was matched to a maximization of the overlap of segmented images. Image series were evaluated with both algorithms and bench marked against a manual motion correction.
Due to the dominating speckle noise in the OCT images and tissue motion perpendicular to the plane of the cross-sectional images, the correlation algorithms was not able to correctly determine a correct tissue motion in all cases. Results of the optimization algorithms were more reliable after dedicated preprocessing of the images. In cases of strong motion both algorithms failed.
In conclusion, automatic motion correction of mOCT image series taken from mice trachea is possible. However, at the current stage manual supervision is still necessary.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
Effective mucus transport in the airways is essential for infection defense. Malfunction caused by diseases like cystic fibrosis (CF) can result in severe and even life threatening complications. Time resolved imaging of mucus transport in vivo is essential to get mechanistic insight in factors influencing the transport and for developing and testing therapeutic interventions to increase mucus transport.
Microscopic OCT (mOCT) was used successfully to image mucus transport in trachea of spontaneous breathing mice. Image series over more than 2 hours containing 35,000 frames were captured in wild type (WT) and βENaC overexpressing mice, which served as a model for CF. In order to evaluate these large amount of data an automatic quantitative evaluation is need. This has to include an efficient correction of tissue motion and an automatic identification and rejection of non-evaluable frames.
In this study we compared two algorithms for motion correction. A pairwise correlation of the different frame for calculation of the motion vector was matched to a maximization of the overlap of segmented images. Image series were evaluated with both algorithms and bench marked against a manual motion correction.
Due to the dominating speckle noise in the OCT images and tissue motion perpendicular to the plane of the cross-sectional images, the correlation algorithms was not able to correctly determine a correct tissue motion in all cases. Results of the optimization algorithms were more reliable after dedicated preprocessing of the images. In cases of strong motion both algorithms failed.
In conclusion, automatic motion correction of mOCT image series taken from mice trachea is possible. However, at the current stage manual supervision is still necessary. |