Theoretical and experimental study of ON-Resonance Saturation, an MRI sequence for positive contrast with superparamagnetic nanoparticles.
Fiche publication
Date publication
mars 2015
Journal
Journal of magnetic resonance (San Diego, Calif. : 1997)
Auteurs
Membres identifiés du Cancéropôle Est :
Dr PO Chrystelle
Tous les auteurs :
Delangre S, Vuong QL, Henrard D, Magat J, Po C, Gallez B, Gossuin Y
Lien Pubmed
Résumé
Superparamagnetic iron oxide nanoparticles (SPM particles) are widely used in MRI as negative contrast agents. Their detection is sometimes difficult because negative contrast can be caused by different artifacts. To overcome this problem, MRI protocols achieving positive contrast specific to SPM particles were developed such as the ON-Resonance Saturation (ONRS) sequence. The aim of the present work is to achieve a bottom-up study of the ONRS sequence by an understanding of the physical mechanisms leading to positive contrast. A complete theoretical modeling, a novel numerical simulation approach and experiments on agarose gel phantoms on a 11.7 T MRI system were carried out for this purpose. The influence of the particle properties and concentration - as well as the effect of the sequence parameters on the contrast - were investigated. It was observed that theory and experiments were in strong agreement. The tools developed in this work allowed to predict the parameters leading to the maximum contrast. For example, particles presenting a low transverse relaxivity can provide an interesting positive contrast after optimization of their concentration in the sample.
Mots clés
Contrast agents, Iron oxide nanoparticles, Magnetic resonance imaging, Off-resonance imaging, Positive contrast imaging, Superparamagnetic nanoparticles
Référence
J Magn Reson. 2015 Mar;252:151-62