title: Theoretical and experimental study of ON-Resonance Saturation, an MRI sequence for positive contrast with superparamagnetic nanoparticles.
abstract: 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.
authors.affiliation: Biomedical Physics Department, University of Mons, 24, Avenue du Champ de Mars, 7000 Mons, Belgium.
authors.forename: S
authors.initials: S
authors.lastname: Delangre
authors.affiliation: Biomedical Physics Department, University of Mons, 24, Avenue du Champ de Mars, 7000 Mons, Belgium.
authors.forename: Q L
authors.initials: QL
authors.lastname: Vuong
authors.affiliation: Biomedical Physics Department, University of Mons, 24, Avenue du Champ de Mars, 7000 Mons, Belgium.
authors.forename: D
authors.initials: D
authors.lastname: Henrard
authors.affiliation: Biomedical Magnetic Resonance Research Group, Louvain Drug Research Institute, Université Catholique de Louvain, 73, Avenue E. Mounier, 1200 Brussels, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Magat
authors.affiliation: Biomedical Magnetic Resonance Research Group, Louvain Drug Research Institute, Université Catholique de Louvain, 73, Avenue E. Mounier, 1200 Brussels, Belgium.
authors.forename: C
authors.initials: C
authors.lastname: Po
authors.affiliation: Biomedical Magnetic Resonance Research Group, Louvain Drug Research Institute, Université Catholique de Louvain, 73, Avenue E. Mounier, 1200 Brussels, Belgium.
authors.forename: B
authors.initials: B
authors.lastname: Gallez
authors.affiliation: Biomedical Physics Department, University of Mons, 24, Avenue du Champ de Mars, 7000 Mons, Belgium. Electronic address: yves.gossuin@umons.ac.be.
authors.forename: Y
authors.initials: Y
authors.lastname: Gossuin
mesh_terms: D000465:Algorithms; D001921:Brain / Q000033:anatomy & histology*; D003198:Computer Simulation; D003287:Contrast Media / Q000737:chemistry*; D003911:Dextrans / Q000737:chemistry*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D008954:Models, Biological; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
chemical_list: D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; C097921:ferumoxtran-10
keywords: Contrast agents; Iron oxide nanoparticles; Magnetic resonance imaging; Off-resonance imaging; Positive contrast imaging; Superparamagnetic nanoparticles