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Magnetic resonance relaxation induced by superparamagnetic particles used as contrast agents in magnetic resonance imaging: a theoretical review
Author(s) -
Vuong Quoc Lam,
Gillis Pierre,
Roch Alain,
Gossuin Yves
Publication year - 2017
Publication title -
wiley interdisciplinary reviews: nanomedicine and nanobiotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.175
H-Index - 72
eISSN - 1939-0041
pISSN - 1939-5116
DOI - 10.1002/wnan.1468
Subject(s) - relaxation (psychology) , superparamagnetism , magnetic resonance imaging , nuclear magnetic resonance , spin echo , spin–spin relaxation , magnetic field , condensed matter physics , relaxometry , magnetic nanoparticles , physics of magnetic resonance imaging , resonance (particle physics) , magnetization , spin–lattice relaxation , materials science , physics , nanoparticle , paramagnetism , nanotechnology , atomic physics , quantum mechanics , medicine , psychology , social psychology , radiology
Superparamagnetic nanoparticles are used as contrast agents in magnetic resonance imaging and allow, for example, the detection of tumors or the tracking of stem cells in vivo . By producing magnetic inhomogeneities, they influence the nuclear magnetic relaxation times, which results in a darkening, on the image, of the region containing these particles. A great number of studies have been devoted to their magnetic properties, to their synthesis and to their influence on nuclear magnetic relaxation. The theoretical and fundamental understanding of the behavior of these particles is a necessary step in predicting their efficiency as contrast agents, or to be able to experimentally obtain some of their properties from a nuclear magnetic resonance measurement. Many relaxation models have been published, and choosing one of them is not always easy, many parameters and conditions have to be taken into account. Relaxation induced by superparamagnetic particles is generally attributed to an outersphere relaxation mechanism. Each model can only be used under specific conditions (motional averaging regime, static regime, high magnetic field, etc.) or for a particular sequence (Carr‐Purcell‐Meiboom‐Gill, spin echo, free‐induction decay, nuclear magnetic relaxation dispersion profile, etc.). The parameters included in the equations must be carefully interpreted. In some more complex conditions, simulations are necessary to be able to predict the relaxation rates. A good agreement is usually observed between the theoretical predictions and the experimental results, although some data still cannot be fully understood, such as the dependence of the transverse relaxation on the magnetic field. WIREs Nanomed Nanobiotechnol 2017, 9:e1468. doi: 10.1002/wnan.1468 This article is categorized under: Diagnostic Tools > Diagnostic Nanodevices Diagnostic Tools > In Vivo Nanodiagnostics and Imaging