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Session: Arteries
Session starts: Thursday 24 January, 10:30
Presentation starts: 11:45
Room: Lecture room 536

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Roy van Hees (Eindhoven University of Technology)
Frans van de Vosse (Eindhoven University of Technology)
Richard Lopata (Eindhoven University of Technology)

Abstract:
The presence of haemorrhages in the carotid artery is a major risk factor for stroke. The superficial location of the carotid artery makes it very suitable for photoacoustic imaging (PAI). By using multiple wavelengths, it is possible to detect haemorrhages by searching for sites with a high ratio of deoxyhaemoglobin / oxyhaemoglobin. This approach requires at least two wavelengths of light: one wavelength with a high response for both oxy- and deoxyhaemoglobin to estimate the total blood volume and one wavelength with a large difference in response of both constituents. An approach using a single wavelength would lower the requirements of the laser system used and therefore allow for more compact, handheld photoacoustic systems, for the detection of haemorrhages. Aim of this study is to develop a method to detect haemorrhages in the carotid artery using a single wavelength approach combined with novel flow measurement techniques. Conventional flow measurement techniques such as pulsed wave Doppler and colour flow imaging employ a so called “wall filter” to filter out wall motion, as to only measure blood flow. These wall filters employ temporal filtering and although successful at filtering out wall motion, these filters also discard the flow resulting from microvasculature. To properly detect this flow, which is essential for the reliable detection of haemorrhages using a single wavelength approach, a filtering method employing singular value detection is used instead, as described by Charlie Demené et al . Preliminary tests using polyvinyl alcohol gel phantoms, with a lumen with a diameter of 3 mm, a minichannel containing a haemorrhage with a 1 mm diameter and microchannels of a 0.25 mm diameter show that wall filtering using singular value decomposition is a viable approach. Photoacoustic measurements are still ongoing.