Select Listing of Scientific Papers and Posters Citing Aspect Imaging M-Series Compact MRI Systems (original) (raw)
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Revisiting an old friend: manganese-based MRI contrast agents
Wiley interdisciplinary reviews. Nanomedicine and nanobiotechnology, 2010
Non-invasive cellular and molecular imaging techniques are emerging as a multidisciplinary field that offers promise in understanding the components, processes, dynamics and therapies of disease at a molecular level. Magnetic resonance imaging (MRI) is an attractive technique due to the absence of radiation and high spatial resolution which makes it advantageous over techniques involving radioisotopes. Typically paramagnetic and superparamagnetic metals are used as contrast materials for MR based techniques. Gadolinium has been the predominant paramagnetic contrast metal until the discovery and association of the metal with nephrogenic systemic fibrosis (NSF) in some patients with severe renal or kidney disease. Manganese was one of the earliest reported examples of paramagnetic contrast material for MRI because of its efficient positive contrast enhancement. In this review manganese based contrast agent approaches will be presented with a particular emphasis on nanoparticulate agen...
Manganese-based MRI contrast agents: past, present and future
Tetrahedron, 2011
Paramagnetic and superparamagnetic metals are used as contrast materials for magnetic resonance (MR) based techniques. Lanthanide metal gadolinium (Gd) has been the most widely explored, predominant paramagnetic contrast agent until the discovery and association of the metal with nephrogenic systemic fibrosis (NSF), a rare but serious side effects in patients with renal or kidney problems. Manganese was one of the earliest reported examples of paramagnetic contrast material for MRI because of its efficient positive contrast enhancement. In this review, manganese based contrast agent approaches are discussed with a particular emphasis on their synthetic approaches. Both small molecules based typical blood pool contrast agents and more recently developed novel nanometer sized materials are reviewed focusing on a number of successful molecular imaging examples.
The Japan Society of Applied Physics, 2017
MRI technique is a well-known noninvasive imaging technique based on Magnetic Resonance. However, it is difficult to apply this technique for tumor imaging. This is because the tumor physical property is mostly identical with the surrounding tissue, therefore it shows the same contrast during MR Imaging. Currently, the gadolinium (Gd) based contrast agent such as Magnevist® is injected into the patience prior the imaging to effectively change the magnetic property (T1 brightening effect) of the tumor cell. Although Gd is effective, it is dangerous for our body as humans do not have a metabolic pathway for Gd. The use of Gd based agents has also been linked to nephrogenic systemic fibrosis (NSF) in patients. It is important that we develop a new generation of benign contrast agents that are competitive with commercial Gd based contrast agents. As previously reported, Mn8Fe4VBA magnetic cluster encapsulated in polymer nanoparticles (NPs) represents a potential candidate as contrast ag...
Nanoparticles in magnetic resonance imaging: from simple to dual contrast agents
International Journal of Nanomedicine, 2015
Magnetic resonance imaging (MRI) has become one of the most widely used and powerful tools for noninvasive clinical diagnosis owing to its high degree of soft tissue contrast, spatial resolution, and depth of penetration. MRI signal intensity is related to the relaxation times (T 1 , spin-lattice relaxation and T 2 , spin-spin relaxation) of in vivo water protons. To increase contrast, various inorganic nanoparticles and complexes (the so-called contrast agents) are administered prior to the scanning. Shortening T 1 and T 2 increases the corresponding relaxation rates, 1/T 1 and 1/T 2 , producing hyperintense and hypointense signals respectively in shorter times. Moreover, the signal-to-noise ratio can be improved with the acquisition of a large number of measurements. The contrast agents used are generally based on either iron oxide nanoparticles or ferrites, providing negative contrast in T 2-weighted images; or complexes of lanthanide metals (mostly containing gadolinium ions), providing positive contrast in T 1-weighted images. Recently, lanthanide complexes have been immobilized in nanostructured materials in order to develop a new class of contrast agents with functions including blood-pool and organ (or tumor) targeting. Meanwhile, to overcome the limitations of individual imaging modalities, multimodal imaging techniques have been developed. An important challenge is to design allin-one contrast agents that can be detected by multimodal techniques. Magnetoliposomes are efficient multimodal contrast agents. They can simultaneously bear both kinds of contrast and can, furthermore, incorporate targeting ligands and chains of polyethylene glycol to enhance the accumulation of nanoparticles at the site of interest and the bioavailability, respectively. Here, we review the most important characteristics of the nanoparticles or complexes used as MRI contrast agents.
Artificial Cells, Nanomedicine, and Biotechnology, 2015
Today, technologies based on magnetic nanoparticles (MNPs) are regularly applied to biological systems with diagnostic or therapeutic aims. Nanoparticles made of the elements iron (Fe), gadolinium (Gd) or manganese (Mn) are generally used in many diagnostic applications performed under magnetic resonance imaging (MRI). Similar to molecular-based contrast agents, nanoparticles can be used to increase the resolution of imaging while offering well biocompatibility, poisonousness and biodistribution. Application of MNPs enhanced MRI sensitivity due to the accumulation of iron in the liver caused by discriminating action of the hepatobiliary system. The aim of this study is about the use, properties and advantages of MNPs in MRI.
2016
Applications of magnetic nanoparticles (MNPs) as Magnetic resonance imaging (MRI) contrast agent have been widely developed during recent years. MNPs have some unique featuresthat make them interesting option in biomedical applications. While almost all contrast agents for MRI affect both T1 and T2,the selective effects of MNPs on one of T1 or T2 is usually more prominent, leading to the division of these probes to contrast agents of T1 and T2. Among MNPs, paramagnetic NPs can affect T1relaxivity, called as T1weighted contrast agent, whereas super paramagnetic NPs are known as T2-weighted contrast agent. Due to high cellular adsorption of MNPs, they can provide helpful differences between different cell types. The present study reviews the recent advances in applications of MNPs as contrast agents in MRI and focuses on the clinical applications of these techniques in different diseases.
Magnetic nanoparticles as MRI contrast agents
Science-Business eXchange
Magnetic Resonance Imaging (MRI) is a non-invasive imaging modality that offers both anatomical and functional information. Intrinsic longitudinal and transverse relaxation times (T 1 and T 2 , respectively) provide tools to manipulate image contrast. Additional control is yielded when paramagnetic and magnetic particulate materials are used as contrast materials. Superparamagnetic particles are mostly synthesized from iron oxide and are usually coated with polymers and functional particles to offer multifunctional biomedical applications. The latter include not only MRI but also cancer treatment through drug delivery and hyperthermia. This Chapter reviews the fundamental dipole-dipole diamagnetic proton relaxation mechanism dominant in water followed by a brief description of the use of gadolinium complexes as MRI contrast agent. Finally, a description of the important chemical and physical properties of magnetic nanoparticle (MNP) that define their use as MRI relaxation enhancing agents especially for T 2. The main governing models are described for the different motional regimes with few simulation results demonstrating the applicability of the given equations.
Magnetic Nanomaterials as Contrast Agents for MRI
Materials, 2020
Magnetic Resonance Imaging (MRI) is a powerful, noninvasive and nondestructive technique, capable of providing three-dimensional (3D) images of living organisms. The use of magnetic contrast agents has allowed clinical researchers and analysts to significantly increase the sensitivity and specificity of MRI, since these agents change the intrinsic properties of the tissues within a living organism, increasing the information present in the images. Advances in nanotechnology and materials science, as well as the research of new magnetic effects, have been the driving forces that are propelling forward the use of magnetic nanostructures as promising alternatives to commercial contrast agents used in MRI. This review discusses the principles associated with the use of contrast agents in MRI, as well as the most recent reports focused on nanostructured contrast agents. The potential applications of gadolinium- (Gd) and manganese- (Mn) based nanomaterials and iron oxide nanoparticles in ...