Hinnerk Schulz-Hildebrandt

@article{Schulz-Hildebrandt2018b,

title = {High-speed fiber scanning endoscope for volumetric multi-megahertz optical coherence tomography},

author = {Hinnerk Schulz-Hildebrandt and Tom Pfeiffer and Tim Eixmann and Sabrina Lohmann and Martin Ahrens and Josua Rehra and Wolfgang Draxinger and Peter K\"{o}nig and Robert Huber and Gereon H\"{u}ttmann},

url = {https://www.osapublishing.org/ol/abstract.cfm?uri=ol-43-18-4386#Abstract},

doi = {10.1364/OL.43.004386},

year  = {2018},

date = {2018-09-05},

journal = {Optics Letters},

volume = {43},

number = {18},

pages = {4386-4389},

abstract = {We present a forward-viewing fiber scanning endoscope (FSE) for high-speed volumetric optical coherence tomography (OCT). The reduction in size of the probe was achieved by substituting the focusing optics by an all-fiber-based imaging system which consists of a combination of scanning single-mode fibers, a glass spacer, made from a step-index multi-mode fiber, and a gradient-index fiber. A lateral resolution of 11 μm was achieved at a working distance of 1.2 mm. The newly designed piezo-based FSE has an outer diameter of 1.6 mm and a rigid length of 13.5 mm. By moving the whole imaging optic in spirals for scanning the sample, the beam quality remains constant over the entire field of view with a diameter of 0.8 mm. The scanning frequency was adjusted to 1.22 kHz for use with a 3.28 MHz Fourier domain mode locked OCT system. Densely sampled volumes have been imaged at a rate of 6 volumes per second.



© 2018 Optical Society of America},

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}

@article{Ourak2018,

title = {Combined OCT distance and FBG force sensing cannulation needle for retinal vein cannulation: in vivo animal validation},

author = {Ourak, M. and Smits, J. and Esteveny, L. and Borghesan, G. and Gijbels, A. and Schoevaerdts, L. and Douven, Y. and Scholtes, J. and Lankenau, E. and Eixmann, T. and Schulz-Hildebrandt, Hinnerk and H\"{u}ttmann, Gereon and Kozlovszky, M. and Kronreif, G. and Willekens, K. and Stalmans, P. and Faridpooya, K. and Cereda, M. and Giani, A. and Staurenghi, G. and Reynaerts, D. and Vander Poorten, E. B.},

url = {http://link.springer.com/10.1007/s11548-018-1829-0},

doi = {10.1007/s11548-018-1829-0},

year  = {2018},

date = {2018-07-28},

journal = {International Journal of Computer Assisted Radiology and Surgery},

volume = {13},

number = {107},

pages = {1-9},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@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},

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pubstate = {published},

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}

@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.},

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pubstate = {published},

tppubtype = {article}

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@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.},

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}