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Abstract #3001

Five-Site Modeling of Protons Chemical Exchange Processes for in Vivo CEST-Based Molecular Imaging

Julien Flament1, Benjamin Marty1, Cline Giraudeau1, Sbastien Mriaux1, Julien Valette1, Christelle Mdina2, Caroline Robic2, Marc Port2, Franck Lethimonnier1, Gilles Bloch1, Denis Le Bihan1, Fawzi Boumezbeur1

1NeuroSpin, IBM, Commissariat l'Energie Atomique, Gif-sur-Yvette, France; 2Guerbet, Research Division, Roissy-Charles de Gaulle, France

LipoCEST are a new class of contrast agents for CEST-MRI which provide a tremendous amplification factor but suffer from a quite small chemical shift (2-28 ppm) compared to paramagnetic complexes. Consequently, their detection in vivo is hampered by endogenous Magnetization Transfer contrast. It is therefore important to separate specific LipoCEST signal from endogenous background coming from macromolecules. Thus in this study, we propose to characterize water exchange processes using a five-site model by measuring and fitting the Z-spectrum of each tissular compartment of mouse brain in order to achieve quantitative CEST imaging with LipoCEST contrast agents.