Involved people: Michel Couprie, Estelle Escudier (Hospital of Paris, INSERM), Qosai Kanafani (DEA student of the UMLV), Laurent Labatte (ESIEE student).
This study proposed to us by Dr. Estelle Escudier, who works with the service of histology of the hospital of Pité-Salpêtrière (Paris).
Certain cells are equipped with a long cilium which is responsible for their mobility. This image (fig. 17(a)), obtained by electronic micrography, shows a transverse section of a cilium. The doctors and biologists showed that the mobility of the cilium is related to the presence of molecular structures called dynein arms. One distinguishes the external arms (1) and the internal arms (2), which are part of some "8"-shaped structures: these structures are the cross-sections of pairs of cylinders called microtubules (3). To contribute to the detection of these arms, one can benefit from the symmetry of the cell to superimpose and add the similar parts of the image and thus to reinforce the signal-to-noise ratio.
The first stage of the analysis consists in locating the positions of the centers of the microtubules. We developed several methods to solve this problem, the goal being the robustness: indeed, among the hundreds of images which we treated, one could note a great variability of the shapes and quantitative parameters (size, luminosity, contrast...). Thanks to the positions obtained, it is possible to identify the parameters of transformations (roughly speaking, rotations) making it possible to superimpose the microtubules. The image obtained (fig. 17(b)) is much more readable than the original image, because the dynein arms are quite localised compared to the microtubules and are reinforced, whereas the noise is not and is thus attenuated by the averaging. This result can be visually exploited by experts, in order to diagnose a class of genetic diseases, the primary ciliary dyskinesia, one of the symptoms of which is a partial or total atrophy of the dynein arms.
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