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MISE EN OEUVRE DE L'IMAGERIE PAR RÉSONANCE MAGNÉTIQUE DU NOYAU D'HÉLIUM-3 HYPERPOLARISÉ ET CONTRIBUTION À LA CARACTÉRISATION TISSULAIRE DES VOIES AÉRIENNES PULMONAIRES

Abstract : This thesis reports the implementation of Magnetic Resonance Imaging (MRI) of hyperpolarised helium-3 at 0.1 T and at 1.5 T in vivo in healthy volunteers. Using hyperpolarised gas in MRI results in two major consequences: the longitudinal magnetisation cannot be restored and strong diffusion effects occur. Considering this, different strategies of acquisition were compared at low field (0.1 T): single-shot sequences (RARE and EPI) and multishot (FLASH). RARE sequence provides nice images in less than 400 ms with only small amounts of gas; EPI is fast but it is hindered by several artefacts such as the Maxwell term artefact; both these sequences are intrinsically limited to a spatial resolution above 5 mm in vivo; FLASH sequence can provide a better resolution but it is less efficient with regards to signal to noise ratio. Low field can be attractive in the hyperpolarised case because the signal to noise ratio is independent of the main magnetic field on a very large range. NMR and MRI CPMG measurements of gas diffusion in lungs are used to underline the alveolar restriction.
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https://tel.archives-ouvertes.fr/tel-00000930
Contributor : Emmanuel Durand <>
Submitted on : Wednesday, December 12, 2001 - 2:29:46 PM
Last modification on : Saturday, October 12, 2019 - 1:15:04 AM
Long-term archiving on: : Friday, April 2, 2010 - 6:07:06 PM

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Emmanuel Durand. MISE EN OEUVRE DE L'IMAGERIE PAR RÉSONANCE MAGNÉTIQUE DU NOYAU D'HÉLIUM-3 HYPERPOLARISÉ ET CONTRIBUTION À LA CARACTÉRISATION TISSULAIRE DES VOIES AÉRIENNES PULMONAIRES. Biophysique [physics.bio-ph]. Université Paris Sud - Paris XI, 2001. Français. ⟨tel-00000930⟩

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