Institutional Repository
Technical University of Crete
Technical University of Crete
EN
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| URI: | http://purl.tuc.gr/dl/dias/4109FA56-D3F7-4ACE-BDBD-8D8428B9FC5E | ||
| Year | 2025 | ||
| Type of Item | Diploma Work | ||
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| Bibliographic Citation | Efstratios Marinou, "Visualizing blood perfusion through LASER speckle imaging", Diploma Work, School of Electrical and Computer Engineering, Technical University of Crete, Chania, Greece, 2025 https://doi.org/10.26233/heallink.tuc.103997 | ||
| Appears in Collections |
Laser Speckle Contrast Imaging (LSCI), a specific method within the broader field of Laser Speckle Imaging, is a non-invasive optical technique, able to visualize motion and flow dynamics through the analysis of speckle patterns. These patterns are formed when the sampling surface is illuminated by coherent light and are captured by a CCD sensor. The simplicity and cost-effectiveness of this configuration are the main factors contributed to LSCI’s growing popularity in the biomedical field. After the acquisition of the raw speckle frames, image processing is performed to extract local intensity contrast. This contrast is indicative of speckle pattern’s decorrelation which, in turn, is related to motion. In fact, through a complex statistical analysis, contrast can be linked to blood flow velocity. Among biomedical applications, blood perfusion imaging is the most prevalent, as it benefits significantly from the technique’s real-time and label-free operation. This work is structured in two main parts. First, a general review of speckle metrology and its applications, along with a description on the biological importance of blood perfusion – providing all the essential foundation for the specific experimental section. The second part of the Thesis focuses on the laboratory work which investigates the application of LSCI in two distinct use cases. The primary application is the visualization of blood perfusion, specifically superfisial skin perfusion. While LSCI is widely used for blood flow imaging, its application to skin perfusion is limited by the lack of resolvable vascular structure, which restricts the method’s ability to produce vascular maps. For this reason, our system was assessed through well-established occlusion-reperfusion protocol. The secondary use case is a novel application of LSCI: visualizing mechanical oscillations on vibrating membranes. LSCI’s sensitivity proved suitable for the visualiazation of stationary field on oscillating drum’ membranes, a widely unexplored application in the literature. We completed this part of our research by applying the technique to controlled osccilation of a speaker’s membrane providing a semi-quantitative analysis. As per our algorithmic choices, a spatial contrast method (LASCA) was implemented using an open-source toolbox and extended with custom post-processing algorithms. Experimental validation demonstrates that, even with low-cost hardware, LSCI can effectively capture both perfusion trends and dynamic motion. The results highlight the technique’s versatility and potential for accessible biomedical and motion analysis applications.
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