Skip to Main content Skip to Navigation
Theses

Suites Régulières d'Impulsions Radio-Fréquence en Résonance Magnétique. Application à l'IRM.

Abstract : Regular RF pulse trains used in NMR can be studied with simple algorithms of polynomial type using the Z transform. Another simplification is brought by the use of spinors to model the rotations. The first application presented is a ‘peel-off' algorithm which permits the synthesis of selective radiofrequency pulses as the ones used in MRI. This algorithm makes the non linearity of the Bloch equations easy to handle. Some unpublished implementation details are given along with some theoretical results concerning the convergence of the hard pulse train approximation and the prediction of the energy deposition. The same tools are subsequently used to obtain a simplified model of the CPMG and SSFP sequences. The echo to echo rotation is studied and the natural stabilization of the signals is explained by the dispersion of phase. The relaxation processes during such sequences are also modelled in a simplified but widely applicable manner. A previous polynomials stabilization algorithm is explained in terms of a discrete version of the adiabatic principle. The last chapter tackles with a non-CPMG sequence which is insensitive to the initial phase of the magnetization. This sequence is based on a quadratic phase modulation of the RF pulse train.
Complete list of metadatas

Cited literature [140 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-00128349
Contributor : Patrick Le Roux <>
Submitted on : Wednesday, January 31, 2007 - 5:46:00 PM
Last modification on : Thursday, January 11, 2018 - 6:21:25 AM
Document(s) archivé(s) le : Friday, September 21, 2012 - 10:46:22 AM

Identifiers

  • HAL Id : tel-00128349, version 1

Collections

Citation

Patrick Le Roux. Suites Régulières d'Impulsions Radio-Fréquence en Résonance Magnétique. Application à l'IRM.. Physique [physics]. Université Paris Sud - Paris XI, 2006. Français. ⟨tel-00128349⟩

Share

Metrics

Record views

326

Files downloads

1007