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Insights into the use of paramagnetic Gd(III) complexes in MR‐molecular imaging investigations
Author(s) -
Aime Silvio,
Cabella Claudia,
Colombatto Sebastiano,
Geninatti Crich Simonetta,
Gianolio Eliana,
Maggioni Fabio
Publication year - 2002
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.10180
Subject(s) - gadolinium , paramagnetism , context (archaeology) , magnetic resonance imaging , molecular imaging , visualization , internalization , relaxation (psychology) , computer science , chemistry , small molecule , nuclear magnetic resonance , nanotechnology , materials science , cell , physics , medicine , biology , artificial intelligence , biochemistry , neuroscience , radiology , quantum mechanics , in vivo , paleontology , microbiology and biotechnology , organic chemistry
Can gadolinium III [Gd(III)] complexes be considered good candidates for magnetic resonance (MR)‐molecular imaging studies? In this review article, we examine the principal issues that are the basis of successful use of Gd‐based protocols in molecular imaging applications. High relaxivity is the primary requisite. Therefore, the design of such paramagnetic probes has to be pursued keeping in mind the relationships between structure, dynamics, and the relevant parameters involved in paramagnetic relaxation processes. Moreover, the limited number of target molecules on cellular membranes makes it necessary to define strategies aimed at delivering many Gd‐containing moieties to the sites of interest. Examples are reported for the attainment of very high relaxivities for the design of new routes for pursuing the accumulation of small sized Gd(III) complexes at the targeting sites. An efficient cellular uptake of Gd‐containing probes is the key step for attaining the visualization of targeted cells by MR imaging, and selected examples are reported. In this context, the problem of the assessment of the minimum amount of Gd(III) complexes necessary for the MR imaging‐visualization of cells has been addressed by reporting the authors' observations on the cell‐internalization of Gd(III) complexes. A particularly efficient delivery system is represented by Gd‐loaded apoferritin, which allows the MR visualization of hepatocytes when the number of Gd‐complexes per cell is 4 ± 1 × 10 7 . Finally, the potential of responsive systems is considered by outlining the exploitation of the amplification effect brought about by the action of a specific enzymatic activity on the relaxivity of a suitably functionalized Gd(III) complex. J. Magn. Reson. Imaging 2002;16:394–406. © 2002 Wiley‐Liss, Inc.