In the biomedical domain, the main goal is to found new imaging techniques of soft tissues with different scales in time and space. The first priority of this projects concern development of elastography for early diagnosis of cancer, i.e. its therapy (elastography is a method which allow to quantify the viscoelastic properties of soft tissues). The new method that we want to apply, allows to map with a MRI system the low frequency shear wave propagation in biological soft tissues; directly related to the local viscoelastic properties of soft tissues. Afterwards inverse problem and reconstruction methods allow to map the viscoelastic properties of the medium. With this kind of technique, a new way is open for diagnosis of some cancer (lungs, breast, prostate, liver) allowing an examination equivalent to deep palpation directly into the organs. Like this we will can restrict the number of biopsy and/or surgery. This goal is of a great interest in socioeconomic terms and a start-up has been created on this subject: " supersonic imagine ".

To realize this project, we propose to combine MRI imaging and ultrasound imaging. Ultrasound allows producing mechanical shear waves inside the medium by generating focalized acoustic pressure zones. This allow to solve an delicate problem of elastography : shear waves generation with enough amplitudes at the studied zone. Moreover, the ultrasound emission is fully programmable and allows controling the direction of propagation of plane shear wave. Like this, a full 3D mapping of the viscoelastic anisotropic properties of soft tissues is possible. These properties are crucial in the developement of malign tumors.

So as to reach our objectives, the ESPCI gets MRI system for micro-imaging (7 Tesla). It could be used for in vivo and in vitro studies of specimens or small animals. The spatial resolution of such an equipment will allows us to investigate relations with results obtain on a full body MRI system (1.5 Tesla). Like this we will be able to study the link between elasticity at the scale of the cells (microscopic) and at the level of the organs (macroscopic). As a part of this program, a strong collaboration with a clinical team will be engage (Pr. Jacques Bittoun team at the Kremlin Bicêtre hospital).