CEST and PARACEST MR contrast agents
GE Global Research Center, Niskayuna, NY, USA.Acta Radiologica (Impact Factor: 1.6). 10/2010; 51(8):910-23. DOI: 10.3109/02841851.2010.502126
In this review we describe the status of development for a new class of magnetic resonance (MR) contrast agents, based on chemical exchange saturation transfer (CEST). The mathematics and physics relevant to the description of the CEST effect in MR are presented in an appendix published in the online version only. We discuss the issues arising when translating in vitro results obtained with CEST agents to using these MR agents in in vivo model studies and in humans. Examples are given on how these agents are imaged in vivo. We summarize the status of development of these CEST agents, and speculate about the next steps that may be taken towards the demonstration of CEST MR imaging in clinical applications.
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- "Lauffer briefly discussed the properties of copper as a platform for the design of imaging agents 25 years ago, deeming it unsuitable for use due to its poor relaxivity (Lauffer 1987). However, with the advent of better imaging software, access to higher field strengths, more sophisticated pulse sequences and the emergence of chemical exchange saturation transfer (CEST) as a relaxation mechanism, the need for metals with such high relaxivity may be coming to an end (De Leon- Rodriguez et al. 2009; Aime et al. 2009; Hancu et al. 2010; Sherry and Wu 2013). The design of MRI contrast agents has developed significantly over the Table 1 The properties of gadolinium and certain first row transition metal species key to their ability to perform as contrast agents (Tobe 1972; Weast 1980) No. unpaired electrons and relevant oxidation state "
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ABSTRACT: Magnetic resonance imaging (MRI) has become a prominent imaging technique in medicine. Gadoliniumbased contrast agents are extensively used to enhance the contrast between normal and diseased tissues through MRI scans. The article illustrates the paramount significance of such contrast agents in MRI applications. Clinically approved contrast agents as well as those in trial period are discussed. Important parameters, i.e. hydration number, rotational correlation time, and mean residence lifetime, influencing the relaxivity (sensitivity) of such agents are described in detail. Various approaches towards relaxivity enhancement are discussed with appropriate examples from the recent literature. A decrease in the Gdwater proton distance results in significant relaxivity enhancement. A comprehensive classification and explanation of Gd3+-based contrast agents are presented. Each class is explained with suitable examples. The stability of contrast agents is dependent on their chemical structure. Future contrast agents need to be tissue specific of high relaxivity, low toxicity, and lower administered dose for in vivo use.Journal of Structural Chemistry 02/2013; 54(1). DOI:10.1134/S002247661301037X · 0.51 Impact Factor