Blanc SVSE 5 - Blanc - SVSE 5 - Physique, chimie du vivant et innovations biotechnologiques

Endoscopic Mueller Imaging – IMULE

Novel technique for endoscopic imaging dedicated to the diagnosis of cancer pathologies

The project aims to bring together, for the first time, an imaging technique able to identify, at an early stage, the presence of a malignancy in biological tissue (Mueller polarimetry), and imaging of deep organs through an endoscopic fiber. Thus, the use of painful and costly biopsies should be reduced.

improvement of diagnosis and better location of suspect sites to reduce the use of biopsies

Since the 1990s, optical techniques for medical diagnosis have seen considerable interest, motivated by their non-destructive, minimally invasive and non-contact features. Among them, those based on polarimetry can show contrasts imperceptible with other means, and thus they can reveal potentially cancerous regions. This is particularly the case of Mueller polarimetry, which is the most complete polarimetric technique. But so far, it can not be used to characterize deep organs in vivo in situ because it seems to be not compatible with the required endoscopic techniques (where light is guided toward the target through an optical fiber). This is due to the fact that optical fibers are birefringent components, likely to change the polarisation state of light (i.e. the parameter to be measured), in an uncontrollable and time dependent manner. The project specifically aims to offer an original solution to get rid of the undesirable contribution of the fiber, in order to achieve, for the first time, a complete characterization of Mueller biological tissue through a optical fiber. The success of the project will open the way for a significant expansion of Mueller imaging in the field of biomedical diagnosis, since it makes possible the polarimetric characterization of tissue accessible by endoscopic way only, thus reducing the frequency of the use of biopsy samples.

A measurement of the Mueller matrix is performed over the assembly «fiber on the forward path - target tissue - fiber on the backward path« at a given wavelength. Then it is performed on the fiber only, at a close wavelength reflected at the output. The differential analysis of the two matrices eliminates the contribution of the fiber endoscope and derives the desired polarimetric response of the target tissue.




The goal of the "IMULE" project (for "Imagerie de Mueller Endoscopique" i.e. "Endoscopic Mueller Imaging") is to demonstrate the very first characterization of a sample of interest, by Mueller polarimetry, through an optical fibre. The main targeted applications are in the domain of the support to medical diagnosis. They concern the early detection of dysplasias, likely to degenerate in cancer, and accessible only endoscopically. The main relevant specialities are gastroenterology, gynaecology and pneumology. One of the operational results of the project will be to open the way to the development of a remote investigation tool, minimally invasive, able to reduce the numbers of required biopsies which are expensive, time consuming and often painful operations.
The main scientific challenge to take up consists in obtaining a precise information on the polarimetric response of a sample, due to light interaction in media with thicknesses between 0.1 and 1 mm, whereas the polarisation of the probing beam and that of the backscattered light are deeply modified when propagating along the meter-long fibre (10^3 to 10^4 times thicker than the sample). The modifications of the polarisation states in the fibre cannot be known and they significantly change when the fibre is manipulated (effects of bendings, pressure, twists…).
The consortium constituted for the project includes three complementary partners: the "Laboratoire de Physique des Interfaces et des Couches Minces (LPICM, UMR CNRS 7647) from Ecole Polytechnique in Palaiseau, the Photonics department of Xlim Institute (UMR CNRS 6172) in Limoges and the anathomopathology department from the "Institut Mutualiste Montsouris", a hospital in Paris.
LPICM is worldwide recognized for its work dealing with the conception of Mueller polarimeters dedicated to thin films characterisation for optics and electronics, and for its recent research on polarimetric techniques applied to cervical and colon cancer detection. For its part, for many years, Xlim has conceived, manufactured and characterised classical and non-conventional silica optical fibres and it has recently patented the very first polarimetric imaging device operating through an optical fibre (measure of degree of polarisation and of linear birefringence). At last, the anatomopathologists from IMM, already strongly involved in past and current collaborations with LPICM, will validate the studied process on biopsies characterised also by classical techniques.
The main point at the origin of the IMULE project is to simultaneously measure the Mueller matrix of the fibre and that of the sample probed through this fibre. To this end, several solutions will be explored. In addition, the decomposition techniques of Mueller matrices available at LPICM, may make it possible to recover the Mueller matrix of the sample even when the fibre matrix is not well known.
Each solution will be implemented and cross comparisons of measurable parameters, sensitivity and accuracy will be systematically achieved, first with well-known targets, then with less cooperative targets and finally with biological samples.
The IMULE project will improve Mueller imaging techniques, and it will significantly push back the limits of their application domains. In case of success, valorisation will be possible (i) by creating a novel type of microendoscope (polarimetric microendoscope) (ii) or by including the process in existing intensimetric endoscopes.

Project coordination


The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.



Help of the ANR 409,999 euros
Beginning and duration of the scientific project: - 36 Months

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