As dental caries is one of the most common diseases, the early and noninvasive detection of carious lesions plays an important role in public health care. Optical coherence tomography (OCT) with its ability of depth-resolved, high-resolution, noninvasive, fast imaging has been previously recognized as a promising tool in dentistry. Additionally, polarization sensitive imaging provides quantitative measures on the birefringent tissue properties and can be utilized for imaging dental tissue, especially enamel and dentin. By imaging three exemplary tooth samples ex vivo with proximal white spot, brown spot, and cavity, we show that the combination of polarization sensitive OCT and the degree of polarization uniformity (DOPU) algorithm is a promising approach for the detection of proximal carious lesions due to the depolarization contrast of demineralized tissue. Furthermore, we investigate different sizes of the DOPU evaluation kernel on the resulting contrast and conclude a suitable value for this application. We propose that DOPU provides an easy to interpret image representation and appropriate contrast for possible future screening applications in early caries diagnostics.

The common way to diagnose hard and soft tissue irregularities in the oral cavity is initially the visual inspection by an experienced dentist followed by further medical examinations, such as radiological imaging and/or histopathological investigation. For the diagnosis of oral hard and soft tissues, the detection of early transformations is mostly hampered by poor visual access, low specificity of the diagnosis techniques, and/or limited feasibility of frequent screenings. Therefore, optical noninvasive diagnosis of oral tissue is promising to improve the accuracy of oral screening. Considering this demand, a rigid handheld endoscopic scanner was developed for optical coherence tomography (OCT). The novelty is the usage of a commercially near-infrared endoscope with fitting optics in combination with an established spectral-domain OCT system of our workgroup. By reaching a high spatial resolution, in vivo images of anterior and especially posterior dental and mucosal tissues were obtained from the oral cavity of two volunteers. The convincing image quality of the endoscopic OCT device is particularly obvious for the imaging of different regions of the human soft palate with highly scattering fibrous layer and capillary network within the lamina propria.

This work deals with possibilities of registration of retinal images from different mo-dalities, concretely optical coherence tomography (OCT), scanning laser ophthalmoscopy (SLO) and fundus camera. In first stage is the interest focused on registration of SLO and fundus images, which will serve to determine area of interest for consecutive registration of OCT data. The final stage is finding correct location of OCT B-scans in fundus image. On the basis of the studied methods of registration was chosen method making use of computation of correlation coefficient for both cases. For finding optimal parameters of registration is used searching through whole space of parameters. In partial stages of the work was created algorithm for alignment of B-scans followed by detection of blood vessels and also simple algorithm for detection of blood vessels from fundus image. For more transparent registration the graphical user interface was created, which allows loading input images and displaying the result in several possible forms.

The master thesis is focused on creating a methodology for quantification of the nerve fiber layer on photographs of the retina. The introductory part of the text presents a medical motivation of the thesis and mentions several studies dealing with this issue. Furthermore, the work describes available textural features and compares their ability to quantify the thickness of the nerve fiber layer. Based on the described knowledge, the methodology to make different regression models enabling prediction of the retinal nerve fiber layer thickness was developed. Then, the methodology was tested on the available image dataset. The results showed, that the outputs of regression models achieve a high correlation between the predicted output and the retinal nerve fiber layer thickness measured by optical coherence tomography. The conclusion discusses an usability of the applied solution.

In this work I present conclusions of clinical-laboratory research focused on the patients with diabetic macular edema (DME). We performed biochemical and immunochemical analyses of vitreous samples that were collected during the pars plana vitrectomy. Moreover, at patients with non-proliferative diabetic retinopathy (NPDR) we assessed morphological characteristics of DME using optical coherence tomography (OCT). According to our findings, the vitreous and serum concentrations of uric acid and glucose were significantly higher in patients with diabetic retinopathy and DME compared to controls. Also total ratio (serum/ vitreous concentration) of uric acid and glucose was in diabetics significantly higher than in controls. The most important determinant of increasing concentration of both uric acid and glucose in the vitreous was the grade of diabetic retinopathy. Moreover, we demonstrated significant correlation between vitreous concentration of uric acid and concentration of the vascular endothelial growth factor (VEGF) in patients with DME and NPDR. We found further, that the volume of the macula (cube volume - CV) computed with the software of Cirrus HD-OCT correlates in diabetics significantly with the vitreous VEGF concentration, but not with uric acid. This OCT parameter could be used to...

In this work I present conclusions of clinical-laboratory research focused on the patients with diabetic macular edema (DME). We performed biochemical and immunochemical analyses of vitreous samples that were collected during the pars plana vitrectomy. Moreover, at patients with non-proliferative diabetic retinopathy (NPDR) we assessed morphological characteristics of DME using optical coherence tomography (OCT). According to our findings, the vitreous and serum concentrations of uric acid and glucose were significantly higher in patients with diabetic retinopathy and DME compared to controls. Also total ratio (serum/ vitreous concentration) of uric acid and glucose was in diabetics significantly higher than in controls. The most important determinant of increasing concentration of both uric acid and glucose in the vitreous was the grade of diabetic retinopathy. Moreover, we demonstrated significant correlation between vitreous concentration of uric acid and concentration of the vascular endothelial growth factor (VEGF) in patients with DME and NPDR. We found further, that the volume of the macula (cube volume - CV) computed with the software of Cirrus HD-OCT correlates in diabetics significantly with the vitreous VEGF concentration, but not with uric acid. This OCT parameter could be used to...

Nichtglaukomatöse Optikusatrophien führen nicht nur zu einer Verminderung der Dicke der retinalen Nervenfaserschicht (RNFL) sondern auch zu einer Reduktion des Makulavolumens. In dieser Arbeit wurde mit Hilfe der optischen Kohärenztomographie (OCT) untersucht, welche Schichten der Makula von Dickenveränderungen als Folge einer Optikusatrophie betroffen sind. Es wurden 27 Patienten mit nichtglaukomatösen Optikusatrophien unterschiedlicher Ätiologie (postneuritische, hereditäre und traumatische Atrophien) und 21 augengesunde Kontrollpersonen untersucht. OCT-Scans der RNFL und der Makula wurden mit Hilfe des Stratus OCT 3000 (Carl Zeiss Meditec) durchgeführt. Die axialen Reflektivitätsprofile der radialen Scans wurden aus den exportierten JPEG-Bildern an zwölf Punkten in je 1,5mm Entfernung von der Foveola vermessen und gemittelt. Das charakteristische Reflektivitätsprofil mit fünf Intensitätsmaxima und vier Intensitätsminima wurde der Lokalisation der einzelnen Makulaschichten zugeordnet. Die von nichtglaukomatöser Optikusatrophie betroffenen Augen wiesen im Vergleich zu den Augen der augengesunden Normalpersonen signifikant (p<0,05) reduzierte RNFL-Dicken (um 35,5% reduziert) und Makulavolumen-Werte (um 11,8% reduziert) auf. Bei allen untersuchten Formen der Optikusatrophie waren nicht nur die makuläre Nervenfaserschicht (MNFL) sondern alle inneren Schichten der Makula verdünnt. Die mittlere Reduktion betrug 21,2% für die MNFL, 39,7% für die Ganglienzellschicht, 33,2% für die innere plexiforme Schicht und 9,4% für die innere Körnerzellschicht im Vergleich zu den Werten der Normalpersonen. Veränderungen der äußeren Netzhautschichten traten nur bei den posttraumatischen Atrophien auf. Eine Beurteilung der Dicke aller einzelnen Netzhautschichten aus OCT-Scans ist mit Hilfe geräteintegrierter Software bisher noch nicht möglich. Die quantitative Analyse der axialen Reflektivitätsprofile aus exportierten OCT-Bildern stellt eine geeignete Methode zur Beschreibung des Verlaufs und der Lokalisation von Makulaveränderungen bei Optikusatrophien verschiedener Genese dar.

The early non-invasive diagnosis of epithelial tissue alterations in daily clinical routine is still challenging. Since optical coherence tomography (OCT) shows the potential to differentiate between benign and malignant tissue of primal endothelium, OCT could be beneficial for the early diagnosis of malignancies in routine health checks. In this research, a new handheld endoscopic scanning unit was designed and connected to a spectral domain OCT system of our workgroup for the in vivo imaging of the human oral mucosa.

Cell transplantation and stem cell therapy are promising approaches for regenerative medicine and are of interest to researchers and clinicians worldwide. However, currently, no imaging technique that allows three-dimensional in vivo inspection of therapeutically administered cells in host tissues is available. Therefore, we investigate magnetomotive optical coherence tomography (MM-OCT) of cells labeled with magnetic particles as a potential noninvasive cell tracking method. We develop magnetomotive imaging of mesenchymal stem cells for future cell therapy monitoring. Cells were labeled with fluorescent iron oxide nanoparticles, embedded in tissue-mimicking agar scaffolds, and imaged using a microscope setup with an integrated MM-OCT probe. Magnetic particle-induced motion in response to a pulsed magnetic field of 0.2 T was successfully detected by OCT speckle variance analysis, and cross-sectional and volumetric OCT scans with highlighted labeled cells were obtained. In parallel, fluorescence microscopy and laser speckle reflectometry were applied as two-dimensional reference modalities to image particle distribution and magnetically induced motion inside the sample, respectively. All three optical imaging modalities were in good agreement with each other. Thus, magnetomotive imaging using iron oxide nanoparticles as cellular contrast agents is a potential technique for enhanced visualization of selected cells in OCT.

Intravital microscopy (IVM) is a well-established imaging technique for real-time monitoring of microscale lung tissue dynamics. Although accepted as a gold standard in respiratory research, its characteristic image features are scarcely understood, especially when trying to determine the actual position of alveolar walls. To allow correct interpretation of these images with respect to the true geometry of the lung parenchyma, we analyzed IVM data of alveoli in a mouse model in comparison with simultaneously acquired optical coherence tomography images. Several IVM characteristics, such as double ring structures or disappearing alveoli in regions of liquid filling, could be identified and related to the position of alveoli relative to each other. Utilizing a ray tracing approach based on an idealized geometry of the mouse lung parenchyma, two major reflection processes could be attributed to the IVM image formation: partial reflection and total internal reflection between adjacent alveoli. Considering the origin of the reflexes, a model was developed to determine the true position of alveolar walls within IVM images. These results allow thorough understanding of IVM data and may serve as a basis for the correction of alveolar sizes for more accurate quantitative analysis within future studies of lung tissue dynamics.