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MRI Contrast Agents: Current Challenges and New Progresses

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Inorganic Chemistry".

Deadline for manuscript submissions: closed (29 February 2024) | Viewed by 5245

Special Issue Editor


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Guest Editor
Department of Life Sciences and Coimbra Chemistry Center, Faculty of Science and Technology, University of Coimbra, Coimbra, Portugal
Interests: biomedical NMR and molecular imaging; development and evaluation of contrast agents for MRI and multimodal imaging; nanosystems for theranostics and multimodal imaging

Special Issue Information

Dear Colleagues,

Magnetic resonance imaging (MRI) is one of the most important clinical imaging modalities, and a large percentage of MRI clinical exams use a gadolinium (Gd) containing contrast agent (CA) to enhance image contrast. The spectacular success of Gd-based contrast agents (GBCAs) stimulated research on various lanthanide chelates for MR applications. This Special Issue of Molecules, entitled “MRI Contrast Agents: Current Challenges and New Frontiers”, aims at including original manuscripts, technical reports, and reviews reporting innovative research on all aspects of MRI CAs as powerful tools in medical diagnostics. These include, but are not limited to, smart/responsive/angiographic Gd3+ and transition metal complexes, such as Fe and Mn at different oxidation states, as well as soft nanomaterials, such as metal labelled micelles, liposomes, dendrimers, carbon-based nanotubes, biopolymers and other aggregates, hard nanomaterials, including iron oxides, ferrites, metal-organic frameworks and Ln3+ containing nanoparticles, and nanocomposites. Nanoplatforms for MRI based multimodal and/or theranostic applications are also included, as well as computer-based modelling of MRI contrast agents and experimental characterization of the systems, working on the basis of nuclear spin relaxation (T1, T2, T2*), chemical exchange saturation transfer (CEST) or PARASHIFT mechanisms. Due to recent reports on adverse effects related to in vivo Gd-release and deposition, focus on the improvement of in vivo stability as well as the exploration of transition metal-based agents and metal-free agents, such as 19F-based MRI agents, organic free radicals, and hyperpolarized probes is an important goal.

Prof. Dr. Carlos Geraldes
Guest Editor

Manuscript Submission Information

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Keywords

  • magnetic resonance imaging (MRI)
  • contrast agents
  • Gd and transition metal complexes
  • physicochemical parameters of complexes
  • responsive/targeted agents
  • CEST/paraCEST/ PARASHIFT probes
  • superparamagnetic nanoparticles
  • lanthanide-based nanoparticles
  • MRI-based multimodal and theranostic nanoparticles

Published Papers (4 papers)

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Research

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12 pages, 1523 KiB  
Article
Metal-Assembled Collagen Peptide Microflorettes as Magnetic Resonance Imaging Agents
by Dawn Ernenwein, Iris Geisler, Anna Pavlishchuk and Jean Chmielewski
Molecules 2023, 28(7), 2953; https://doi.org/10.3390/molecules28072953 - 26 Mar 2023
Viewed by 1386
Abstract
Magnetic resonance imaging (MRI) is a medical imaging technique that provides detailed information on tissues and organs. However, the low sensitivity of the technique requires the use of contrast agents, usually ones that are based on the chelates of gadolinium ions. In an [...] Read more.
Magnetic resonance imaging (MRI) is a medical imaging technique that provides detailed information on tissues and organs. However, the low sensitivity of the technique requires the use of contrast agents, usually ones that are based on the chelates of gadolinium ions. In an effort to improve MRI signal intensity, we developed two strategies whereby the ligand DOTA and Gd(III) ions are contained within Zn(II)-promoted collagen peptide (NCoH) supramolecular assemblies. The DOTA moiety was included in the assembly either via a collagen peptide sidechain (NHdota) or through metal–ligand interactions with a His-tagged DOTA conjugate (DOTA-His6). SEM verified that the morphology of the NCoH assembly was maintained in the presence of the DOTA-containing peptides (microflorettes), and EDX and ICP-MS confirmed that Gd(III) ions were incorporated within the microflorettes. The Gd(III)-loaded DOTA florettes demonstrated higher intensities for the T1-weighted MRI signal and higher longitudinal relaxivity (r1) values, as compared to the clinically used contrast agent Magnevist. Additionally, no appreciable cellular toxicity was observed with the collagen microflorettes loaded with Gd(III). Overall, two peptide-based materials were generated that have potential as MRI contrast agents. Full article
(This article belongs to the Special Issue MRI Contrast Agents: Current Challenges and New Progresses)
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Review

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18 pages, 3768 KiB  
Review
A Review on the Design of Carbon-Based Nanomaterials as MRI Contrast Agents
by Sarah Garifo, Thomas Vangijzegem, Dimitri Stanicki and Sophie Laurent
Molecules 2024, 29(7), 1639; https://doi.org/10.3390/molecules29071639 - 05 Apr 2024
Viewed by 385
Abstract
The administration of magnetic resonance imaging (MRI) contrast agents (CAs) has been conducted since 1988 by clinicians to enhance the clarity and interpretability of MR images. CAs based on gadolinium chelates are the clinical standard used worldwide for the diagnosis of various pathologies, [...] Read more.
The administration of magnetic resonance imaging (MRI) contrast agents (CAs) has been conducted since 1988 by clinicians to enhance the clarity and interpretability of MR images. CAs based on gadolinium chelates are the clinical standard used worldwide for the diagnosis of various pathologies, such as the detection of brain lesions, the visualization of blood vessels, and the assessment of soft tissue disorders. However, due to ongoing concerns associated with the safety of gadolinium-based contrast agents, considerable efforts have been directed towards developing contrast agents with better relaxivities, reduced toxicity, and eventually combined therapeutic modalities. In this context, grafting (or encapsulating) paramagnetic metals or chelates onto (within) carbon-based nanoparticles is a straightforward approach enabling the production of contrast agents with high relaxivities while providing extensive tuneability regarding the functionalization of the nanoparticles. Here, we provide an overview of the parameters defining the efficacy of lanthanide-based contrast agents and the subsequent developments in the field of nanoparticular-based contrast agents incorporating paramagnetic species. Full article
(This article belongs to the Special Issue MRI Contrast Agents: Current Challenges and New Progresses)
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27 pages, 5130 KiB  
Review
Rational Design of Magnetic Nanoparticles as T1–T2 Dual-Mode MRI Contrast Agents
by Carlos F. G. C. Geraldes
Molecules 2024, 29(6), 1352; https://doi.org/10.3390/molecules29061352 - 18 Mar 2024
Viewed by 1139
Abstract
Magnetic nanoparticles (MNPs), either paramagnetic or superparamagnetic depending on their composition and size, have been thoroughly studied as magnetic resonance imaging (MRI) contrast agents using in vitro and in vivo biomedical preclinical studies, while some are clinically used. Their magnetic properties responsible in [...] Read more.
Magnetic nanoparticles (MNPs), either paramagnetic or superparamagnetic depending on their composition and size, have been thoroughly studied as magnetic resonance imaging (MRI) contrast agents using in vitro and in vivo biomedical preclinical studies, while some are clinically used. Their magnetic properties responsible in some cases for high magnetization values, together with large surface area-to-volume ratios and the possibility of surface functionalization, have been used in MRI-based diagnostic and theranostics applications. MNPs are usually used as positive (T1) or negative (T2) MRI contrast agents, causing brightening or darkening of selected regions in MRI images, respectively. This review focusses on recent developments and optimization of MNPs containing Gd, Mn, Fe and other lanthanide ions which may function as dual-mode T1–T2 MRI contrast agents (DMCAs). They induce positive or negative contrast in the same MRI scanner upon changing its operational mode between T1-weighted and T2-weighted pulse sequences. The type of contrast they induce depends critically on their r2/r1 relaxivity ratio, which for DMCAs should be in the 2–10 range of values. After briefly discussing the basic principles of paramagnetic relaxation in MNPs, in this review, the basic strategies for the rational design of DMCAs are presented and typical examples are discussed, including in vivo preclinical applications: (1) the use of NPs with a single type of contrast material, Gd- or Mn-based NPs or superparamagnetic NPs with appropriate size and magnetization to provide T2 and T1 contrast; and (2) inclusion of both types of T1 and T2 contrast materials in the same nanoplatform by changing their relative positions. Full article
(This article belongs to the Special Issue MRI Contrast Agents: Current Challenges and New Progresses)
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25 pages, 2348 KiB  
Review
Mn-Based MRI Contrast Agents: An Overview
by Céline Henoumont, Marie Devreux and Sophie Laurent
Molecules 2023, 28(21), 7275; https://doi.org/10.3390/molecules28217275 - 26 Oct 2023
Cited by 4 | Viewed by 1892
Abstract
MRI contrast agents are required in the clinic to detect some pathologies, such as cancers. Nevertheless, at the moment, only small extracellular and non-specific gadolinium complexes are available for clinicians. Moreover, safety issues have recently emerged concerning the use of gadolinium complexes; hence, [...] Read more.
MRI contrast agents are required in the clinic to detect some pathologies, such as cancers. Nevertheless, at the moment, only small extracellular and non-specific gadolinium complexes are available for clinicians. Moreover, safety issues have recently emerged concerning the use of gadolinium complexes; hence, alternatives are urgently needed. Manganese-based MRI contrast agents could be one of these alternatives and increasing numbers of studies are available in the literature. This review aims at synthesizing all the research, from small Mn complexes to nanoparticular agents, including theranostic agents, to highlight all the efforts already made by the scientific community to obtain highly efficient agents but also evidence of the weaknesses of the developed systems. Full article
(This article belongs to the Special Issue MRI Contrast Agents: Current Challenges and New Progresses)
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