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Accueil > Équipes > OPTique et IMAgerie > Imagerie photoacoustique

Microvascularisation imaging

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Olivier Jacquin, Olivier Hugon, Eric Lacot, Mehdi Inglebert, Vadim Girardeau, Carolina Goloni

We use photoacoustic microscopy for vascularization imaging. In photoacoustic microscopy, as in conventional optical microscopy, the resolution is given by the optical diffraction limit. This remains valid as long as it is possible to focus the light, therefore at depth no larger than a few hundred microns in the biological tissues, depth beyond which the effects of optical diffusion become predominant. The main advantage of optical resolution photoacoustic microscopy (OR-PAM) is to be specifically sensitive to optical absorption, as opposed to the scattering for instance, which provides contrast in optical coherence tomography (OCT). In particular, while fluorescence microscopy requires the injection of exogenous contrast agents to image biological tissues, photoacoustic microscopy can exploit endogenous absorbers of biological tissues such as red blood cells. Vascularization imaging, which is based on the very strong absorption of visible light by red blood cells, is therefore a very important application of photoacoustic microscopy.

We are working in the team on both vasculature models based on microfluidic channels as well as small animal experiments. One of the issues addressed is that of the detection of blood aggregates, with the objective of monitoring the formation of aggregates of red blood cells in the bloodstream in a non-invasive way, through the skin. Blood is indeed a complex fluid whose composition and physical characteristics tell us about the state of health of a patient. The rheology of the blood can be modified by the phenomenon of aggregation of red blood cells which causes coagulation when the blood is at rest, but which can also occur in the circulation for certain pathologies. Too numerous and too large aggregates can cause circulatory complications leading to defective perfusion of certain tissues, ultimately risking their necrosis. Their surveillance is therefore an important health issue for patients.