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Imagerie dynamique et vélocimétrie IRM des gaz hyperpolarisés

Abstract : This work is part of a French project called R-MOD that aims at the development of a morpho-functional simulator of the upper and central airways. Here, hyperpolarized gas (HPG) MRI methods to visualize and quantify gas flows were developed to test the predictions of the simulator.
To reach this goal, a dedicated MR-compatible device was built to administrate HPG in a controlled way and different imaging strategies were evaluated.
A first qualitative approach was based on dynamic imaging of a HPG inspiration. An analysis of this type of experiment was achieved. The temporal evolution of the phenomenon is too high to be correctly imaged with the state-of-the-art techniques. Nevertheless, spatial distribution of the magnetization within the lung reaches an equilibrium state during a stationary inspiration. This equilibrium state depends on parameters that were explored both theoretically and experimentally through several dynamic imaging techniques.
A second approach, more quantitative, is based on phase-contrast velocimetry combined with rapid radial imaging. The technique was first validated on known flow patterns (straight, curved and bifurcating pipes) and then applied on a realistic bronchial tree reconstructed from medical images and compared to computational fluid dynamics simulations. The 3 velocity components were measured within about 1 s, with 1-mm spatial resolution, and a precision of 1cm•s-1. Finally, in vivo feasibility was shown on a human trachea during an inhalation.
This flow characterization technique based on HPG MRI is a promising tool for fluid dynamics studies and for related medical applications.
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https://tel.archives-ouvertes.fr/tel-00083287
Contributor : Ludovic de Rochefort <>
Submitted on : Friday, June 30, 2006 - 1:17:14 AM
Last modification on : Friday, October 23, 2020 - 4:55:06 PM
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Ludovic de Rochefort. Imagerie dynamique et vélocimétrie IRM des gaz hyperpolarisés. Physique [physics]. Université Paris Sud - Paris XI, 2006. Français. ⟨tel-00083287⟩

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