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2014-11-25 - Colloque/Présentation - poster - Anglais - 1 page(s)

Callewaert M., cadiou C, Roulin V.G., Millart E, Andry M.C., Portefaix C., Molinari M., Chuburu F., Muller Robert , Laurent Sophie , Henoumont Céline , Vander Elst Luce , "A nanohydrogel approach to boost the relaxivity of conventional MRI Gd contrast agents" in YBMRS (13ème edition), Spa Sol Cress, Belgique, 2014

  • Codes CREF : Physico-chimie générale (DI1320), Chimie des colloïdes (DI1329)
  • Unités de recherche UMONS : Chimie générale, organique et biomédicale (M108)
  • Instituts UMONS : Institut des Sciences et Technologies de la Santé (Santé), Institut des Biosciences (Biosciences)
  • Centres UMONS : Centre de Recherche en Microscopie et Imagerie Médicale (CMMI)

Abstract(s) :

(Anglais) Magnetic resonance imaging (MRI) is one of the most powerful non-invasive techniques for clinical diagnostic, mainly due to its high anatomical resolution and its speed. MRI relies upon the perturbation by a radio frequency of the relaxation times of water protons, along the longitudinal (T1) and transverse (T2) components of the main applied magnetic field.1 Contrast in MR image results then from the natural variations of the relaxation times (T1 and/or T2) between healthy and diseased tissues. Because these variations are weak, the use of paramagnetic contrast agents (CAs) is often required. The role of these CAs is to shorten the T1 and/or T2 relaxation times of water protons in the tissues.1 The most commonly used contrast agents are gadolinium chelates (GdCAs) and their efficiency to accelerate the relaxation rate is given by their relaxivity r1. Even if these agents have enabled significant progresses they still suffer from some limitations because their relaxivities are far from the ones predicted by the theory.1 In order to circumvent these limitations, we have developed a series of GdCA-loaded polysaccharide-based nanohydrogels (GdCANPs).2 These biocompatible nanohydrogels, elaborated by an easy and robust ionotropic gelation process3 involving chitosan (CH) and hyaluronan (HA), encapsulate GdCAs such as GdDOTA, GdDOTP and MS325 in a highly hydrated nanostructure. In the poster presentation, we will demonstrate that according to the nature of the polymer matrix and to the cross-linking ability of the GdCA, r1 relaxivities per Gd centre as high as 100 s-1 mM-1 at 30 MHz can be reached. The NMRD profiles will confirm that molecular motions of the Gd chelate are effectively restricted and that water access to the inner core of these nanogels is not limited. On T1- and T2-weighted images recorded at 3Teslas, we will show that this relaxation enhancement is clearly translated into a magnified contrast, demonstrating the powerful dual mode imaging capability of such nanosytems.