Blood lipids are one of the main biomarkers for cardiovascular diseases (CVD). Current method for blood lipid assessment requires invasive blood draws, usually after an overnight fast, followed by lab-based testing, makes the technique not suitable for regular monitoring. The limitations of invasive blood testing techniques, alongside the growing evidence supporting the benefits of regular lipid monitoring, particularly after a meal, for better CVD prediction, indicate that there is an unmet need for non-invasive blood lipid assessment. Our lab recently demonstrated the possibility of non-invasive blood lipids monitoring using a diffuse optical technique called shortwave infrared spatial frequency domain imaging (SWIR SFDI). Using SWIR SFDI, we have shown that an increase of blood lipids after a high fat meal that was measured with gold standard blood draw, correlates strongly with an SFDI derived parameter called SWIR-MPI index. While the results were promising, advancements in SFDI instrumentation, modeling, and experiments are needed prior to clinical testing and translation. The work presented in this dissertation was focused on identifying the source of optical contrast induced by blood lipids, and advancing SFDI instrumentation and processing methodology for the goal of developing a clinic-ready optical system for non-invasive blood lipid assessment. To improve SFDI instrumentation, the SFDI parameters were fine-tuned, and a new compact and portable system was developed and assessed for its performance using optical phantoms. A new two-layer model that accounts for the effect of skin was developed to improve SFDI processing methodology when measuring human subjects. The integration of the new instrument and model make SFDI technique more suitable to use for human studies. Next, the effect of lipids on optical properties of blood were investigated through literature reviews, theoretical simulations and ex-vivo experiments on bovine blood. Finally, we conducted a healthy volunteer study to monitor blood lipid alteration after low fat and high fat meal with SFDI. Together, the works in this project advances our comprehension of the optical effects of blood lipids and their association with meal consumption in both healthy individuals and those with dyslipidemia. The innovative technology and the preliminary feasibility study push the boundaries of non-invasive blood lipid assessment, offering promising prospects for translating this technology to clinical settings, thereby enhancing CVD risk assessment. / 2024-08-29T00:00:00Z

Diplomová práce analyzuje postavení státních fondů ve veřejné rozpočtové soustavě. První kapitola obsahuje vysvětlení pojmu fond, obecnou charakteristiku státních fondů, vymezení jejich výhod a nevýhod. Další kapitoly se věnují jednotlivým fondům, které existují v současné době (1. polovina roku 2007) v České republice. Je dodržena stejná struktura: charakteristika fondu, podporované programy a pravidla pro čerpání prostředků, hospodaření fondu. Cílem je rovněž nastínění budoucího vývoje daného fondu a zvýšení informovanosti o této problematice u širší veřejnosti.

The microcirculation system is crucial for the function of delivering biological markers such as oxygen and removing carbon dioxide from all the cells forming the complex ma- trix of tissue in the body. To keep up with the demands of each and every cell, there is a response from the microvasculature - resulting from for instance changes in blood flow to the tissue area. Infections cause disturbances in this important system, which increases the risk of development into one of the world’s most common syndrome - sepsis. This con- dition can be explained as a biological response affecting each and every vital organ, and can as a result of the dysfunction be life threatening. Studies have shown when monitoring pulse and respiratory rate the response is not visually quick enough to be able to determine the gravity in the state of the patient. The primarily chosen biological markers were oxy- genated hemoglobin and deoxygenated hemoglobin present in blood, respectively melanin in the skin. This was performed using the optical instrument Spatial Frequency Domain Imaging in combination with a Tissue Viability Imager respectively an Enhanced Perfusion and Oxygen Saturation-equipment. The formulated aim for this thesis was separated into an optical part and a mathematical modeling part. Regarding the optical section the aim was to understand if there were any optical methods more preferable to detect changes in the microcirculation, whilst the modeling section aimed to understand how to construct the best adjusted model for the changes in the biological markers and how these could be related to sepsis. Spatial Frequency Domain Imaging is an optical technique able to generate two- dimensional maps of the absorption coefficient and the reduced scattering coefficient of a biological tissue surface. The skin of healthy subjects were illuminated with RGB-LEDs to detect the chromophores of interest. The data obtained from the experimental sessions was then collected to work as a base for building a mathematical model. The experimental session was performed with a total of six healthy subjects and the data was collected dur- ing a control-measurement and a simulated sepsis-measurement using a pressure chamber and applying negative pressure to the lower part of the body. The mathematical model was based on theory regarding the biological events of sepsis in the microcirculation and was described by ordinary differential equations. The results were presented in graphs and the resulting model likewise, with an addi- tional figure to describe the source of associated equations written to describe the events. An observation of a distinct difference in the deoxygenated, respectively oxygenated hemoglobin could be observed and did show in general more changes during the measure- ments using a lower body negative pressure chamber. The chosen optical approach was the Spatial Frequency Domain Imaging equipment along with the mathematical model named as the Macro-Micro model due to its more realistic design. Future improvements were dis- cussed and summarized as a repetition of the experimental sessions and including more parameters and relationships between the biological markers and the model. This would contribute to more robust results.

This study investigates the potential of Spatial Frequency Domain Imaging (SFDI) as a non-invasive imaging technique for tissue analysis in the context of Mohs surgery, a standard procedure for skin cancer removal with margin control. The current practice of performing multiple histopathologic sections during the procedure is time-consuming and labor-intensive. SFDI, utilizing optical measurements, offers quantitative imaging of biological tissues, enabling the assessment of their function and structure. This makes it particularly suitable for imaging sensitive tissues like the skin and the eye. By accurately measuring the optical properties of tissues, a deeper understanding of their characteristics and the interaction of light with tissue can be achieved. In this study, a novel transillumination SFDI system was designed and utilized to obtain spectral data from examined 2 mm thick tissue-simulating phantoms. The results demonstrated the potential of the transmission-based SFDI as a valuable tool in tissue analysis,providing rapid and accurate information about tissue properties. The implementation of transmission-based SFDI system holds promise for enhancing tissue-conserving surgeries. By enabling direct analysis of tissue properties at the point of care, this system could eliminate the need for histopathologic processing. Consequently, it can provide rapid and accurate information about tissue characteristics without the need for histopathologic processing, allowing for more precise and efficient surgical procedures and better patient outcomes

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