Here you will find an overview of my scientific work and recent publications.
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.
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  dargestellt.
Sarah Latus; Christoph Otte; Matthias Schlüter; Josua Rehra; Kevin Bizon; Hinnerk Schulz-Hildebrandt; Thore Saathoff; Gereon Hüttmann; Alexander Schlaefer
Medical Image Computing and Computer-Assisted Intervention − MICCAI 2017, vol. 10434, Springer 2017, ISBN: 978-3-319-66185-8.
© 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
Proceedings of the 7th Joint Workshop on New Technologies for Computer/Robot Assisted Surgery, 2017.
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
Proceedings Volume 10037, Photonics in Dermatology and Plastic Surgery, vol. 10037OS, 2017.
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
Proceedings Volume 10041, Optical Techniques in Pulmonary Medicine II, vol. 1004105, 2017.
Hinnerk Schulz-Hildebrandt; Mario Pieper; J Kasper; Nadine Traulsen; Markus Mall; Peter König; Gereon Hüttmann
Pneumologie, vol. 70, no. 07, 2016.
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.
Mario Pieper; Hinnerk Schulz-Hildebrandt; Marcus A Mall; Gereon Hüttmann; Peter König
Pneumologie, vol. 70, 2016.
Ellen Guder; Eva Lankenau; Felix Fleischhauer; Hinnerk Schulz-Hildebrandt; Gereon Hüttmann; HW Pau; Tino Just
In: European Archives of Oto-Rhino-Laryngology, vol. 272, no. 11, pp. 3217-3223, 2015, ISSN: 1434-4726.
© 2014, Springer-Verlag Berlin Heidelberg. A microscope-based optical coherence tomography (OCT) device was used to assess the microanatomy of the tympanic membrane in patients with chronic myringitis. A prospective study was designed for this purpose. OCT measurements of the tympanic membrane were done on 11 patients with myringitis with a microscope-based spectral domain OCT system. The in vivo findings were compared with those findings of a control group consisting of 36 patients with retraction pockets or atrophic tympanic membranes (n = 13), myringosclerosis (n = 12) and perforations (n = 11). In active chronic myringitis, the thickness of the tympanic membrane is increased compared to healthy membranes and to other pathological conditions of the tympanic membrane. Consistent changes of the microanatomy of the tympanic membrane were found in chronic myringitis with OCT. Serial OCT measurements revealed no biofilm suspicious findings in all patients with active chronic myringitis. Intraoperative and in vivo OCT measurements may help to detect microanatomical changes of the tympanic membrane in chronic myringitis and in other conditions of the tympanic membrane.
Felix Fleischhauer; Hinnerk Schulz-Hildebrandt; Tim Bonin; Gereon Hüttmann
Student Conference Medical Engineering Science 2013: Proceedings, vol. 2, GRIN Verlag, 2013.
ptical coherence tomography (OCT) is now state of the art in ophthalmology. Other medical departments, such as otolaryngology, could also benefit from this imaging modality. Polarization is a property which is a benefit to conventional OCT. It can be used in particular to detect birefringent tissue layers. To evaluate possible OCT applications in Ear, Nose and Throat (ENT) department, a fiber-based polarization-sensitive OCT (PS- OCT) is used to measure human ex-vivo tissue biopsies. A total of 58 samples from 20 different tissues were measured.
The measurements show that small biopsies lose their birefrin- gent property, this leads to the assumption that tissue-matrices lose tension and molecular order. Larger samples show phase retardation and are used to detect different birefringent layers of tissue. We also show a method of verifying cancer diagnosis by displaying the tissue layer structure.
As a conclusion, PS-OCT may improve cancer diagnosis in ENT.