Translational Imaging Biomarker Discovery and Quantification in Optoacoustics
Year: 2026
Type: dissertation
Abstract: Medical imaging is essential in modern healthcare for diagnostics, disease monitoring, and treatment planning. The plethora of physical principles underlying established imaging modalities results in inherent trade-offs between contrast, penetration depth, acquisition speed, cost, patient safety, and other critical parameters. Emerging imaging technologies aim to mitigate these limitations, thereby enhancing diagnostic accuracy and reducing dependence on invasive procedures such as biopsies. Optoacoustic imaging (OAI) represents a promising new approach that leverages the optoacoustic effect and enables the combination of optical absorption contrast with spatial resolution comparable to that of sonography, offering rapid and functional data acquisition at low cost. However, the complexity of OAI data necessitates the development of sophisticated image processing algorithms to enable reliable quantification and interpretation of physiological parameters. This thesis focuses on the development and validation of optoacoustic imaging (OAI) biomarkers, with particular emphasis on inflammation assessment, aiming to improve disease monitoring in inflammatory bowel disease (IBD). To this end, OAI was applied in a murine model of chemically induced colitis to evaluate vascular biomarkers proposed in the literature and to explore novel functional indicators of inflammation. Using established clinical reference standards such as endoscopy and histology, OAI-derived parameters were validated at multiple spatial scales. A high-resolution OAI system enabled detailed visualization of inflammation-induced changes in the vascular architecture on a microscopic scale, allowing quantification of structural biomarkers such as vessel diameter, density, and network complexity using a custom-developed image processing pipeline tailored to the OAI data. This contributed to a deeper understanding of the mechanisms by which inflammation alters the optoacoustic properties of the affected tissue. Subsequently, a translational multispectral tomographic OAI setup, comparable to clinical OAI systems, was used to assess functional biomarkers, such as tissue oxygenation, across a larger field of view. This stepwise progression from microscopic to macroscopic imaging was enabled by the development of a transrectal absorber guide—a key technical innovation that serves as a fiducial marker for reliable bowel wall localization during imaging. In addition to preclinical IBD research, this work is embedded in a broader translational framework. Collaborative clinical studies utilized these findings in OAI-based paediatric IBD monitoring and functional gastrointestinal assessment using orally administered contrast agents. Furthermore, other organs and diseases, including kidney perfusion, spinal muscular atrophy, and peripheral artery disease, were investigated using OAI. These complementary efforts support the potential of OAI as a versatile, non-invasive modality as a diagnostic tool in inflammatory and degenerative diseases.
Author: Bühler, Adrian
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7120943096
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