Développement d'un nouveau type de vélocimètre doppler laser, basé sur l'interférométrie optique, pour le monitorage de la perfusion de greffons rénaux. – LDFKidney

The aim of this project concerns the development of a new laser Doppler velocimeter (« Laser Doppler Flowmetry » : LDF) for renal graft monitoring, in order to quantify the renal perfusion during removal and transplantation. The advantages of this system over classical echo-doppler methods rely on the use of a disposable optical fibre comparable to those used with therapeutic lasers for endoscopic surgery. The optical fibre can be placed in contact with the kidney surface during surgical procedure, and left within the drain system for post-operation monitoring. The fibre diameter is small (<0.8mm), components are biocompatible and sterilisable. Classical LDF however raises difficulties linked to the fact that the measurement is local: the method only probes a small volume, of the order of 1mm3. This method is therefore very sensitive to all kind of surface heterogeneities and gives no information about the tissue global perfusion . Furthermore, the irrigation of the small explored volume depends on the pressure caused by the sensor, what is an artefacts source. We propose to carry out an original interferometric method, currently developed in the Laser Physics Laboratory, that can perform time-resolved LDF measurements. It should thus be possible, by selecting long-time travelling light, to explore the tissue dip down, eliminating all the above-mentioned problems. The technical development will consist in realizing and testing a prototype, that should be compact enough to be carried and used without difficulty in a surgical bloc or in an hospital room. An intermediate step will be the development of an integrated microchip for the detection system, in order to multiply the detectors number and to improve the signal to noise ratio.