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Author : João Bruno Figueiredo Livramento
Publisher :
ISBN 13 :
Total Pages : 217 pages
Book Rating : 4.:/5 (428 download)
Download or read book New Strategies for Highly Efficient MRI Contrast Agents written by João Bruno Figueiredo Livramento and published by . This book was released on 2006 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Sabrina Laus
Publisher :
ISBN 13 :
Total Pages : 214 pages
Book Rating : 4.:/5 (853 download)
Download or read book New Strategies for Highly Efficient Medical MRI Contrast Agents written by Sabrina Laus and published by . This book was released on 2005 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Loïck Moriggi
Publisher :
ISBN 13 :
Total Pages : 188 pages
Book Rating : 4.:/5 (428 download)
Download or read book Highly Efficient MRI Contrast Agents written by Loïck Moriggi and published by . This book was released on 2008 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 258 pages
Book Rating : 4.:/5 (123 download)
Download or read book Designing a More Effective MRI Contrast Agent written by and published by . This book was released on 2020 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic resonance imaging (MRI) is a medical imaging technique that provides high-resolution images used for diagnostic medicine while maintaining a superior safety profile compared to other radiative techniques. The administration of gadolinium-based contrast agents (GBCAs) improves the diagnostic power of MRI and have been used clinically for over three decades. Although GBCAs are effective at improving the contrast in the image, their detection limits are high and require a large dose to generate an observable effect. This high dose is the consequence of the current available designs of clinical GBCAs; their structures are not tuned to generate optimal efficacy. Efficacy of GBCAs is defined as relaxivity; how effectively the agent increases the T1 relaxation rate constant of protons on water. The isoelectric structure of the f-orbitals of Gd3+ yields it an effective relaxivity agent. However, Gd3+ is toxic and insoluble in vivo, and is therefore bound as a low molecular weight hydrophilic chelate. The ligand which forms the most kinetically inert and safest GBCA is 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (DOTA). Parameters defined by Solomon, Bloembergen, and Morgan (SBM) describe different factors that influence relaxivity of a GBCA. Two of which have been demonstrated to dramatically influence efficacy: chelate tumbling and water exchange rates. A drawback to current ligand systems are low molecular weight; relaxivity increases with slower tumbling chelates. Current GBCAs have a tumbling rate that is much too rapid to achieve high relaxivities. Secondly, while this value is predominating, it is difficult to ascertain the contribution of other SBM parameters. It had been originally hypothesized that to improve relaxivity, water exchange rate needs to be fast. However, research in our group has demonstrated that a chelate which exchanges water too rapidly suffers from a reduction in its hydration state. The implication of this reduction in hydration state on relaxivity has yet to be fully appreciated. The importance of the influence of SBM parameters on relaxivity is realized when advancements in GBCA technology are applied. The non-specific nature of GBCAs means they cannot directly diagnose pathology. One promising approach to reduce detection limits by increasing specificity in vivo is through bifunctional chelators (BFCs). These ligands have two components: a metal chelating group to bind gadolinium (DOTA), and a reactive moiety that couples with a targeting vector to bind desired biological receptors. This allows for defined bioaccumulation in vivo, resulting in improved diagnostics and lower detection limits. But with several BFCs available commercially, each positioning the vector attachment differently on the DOTA scaffold, the ideal scaffold for BFC design while including the influence of SBM is yet to be established. The three most common strategies of targeting vector attachment are off the tetraaza macrocycle, through a monoamide pendant arm, or off an [alpha]-carbon on the acetate pendant arm. A thorough investigation of these three strategies was explored herein, in which BFC precursors were synthesized, and their structures analyzed relaxometrically. It was found that the attachment strategy significantly impacted water exchange parameters and molecular tumbling, which in turn greatly influenced relaxivity. The experiments conducted herein presented compelling new evidence in the way we define water exchange and hydration state. Studies into derivatives of the macrocycle substituted chelate NB-DOTA presented the impact an extremely rapidly exchanging chelate has on hydration state and its effect on relaxivity. Synthesis and analysis of a new tetra [alpha]-carbon substituted chelate, DOTFA, yielded an exceedingly high relaxivity, as well as an interesting and novel impact on water exchange; there is strong evidence that DOTFA chelates exchange water in a mechanism that is not purely dissociative. Finally, studies into amide substituted chelates provided the expected low relaxivity associated with slow water exchange. Yet, it was demonstrated that changing the type of coordinating monoamide pendant arm, water exchange can be tuned to slightly more optimal values. These systematic studies provided novel insight how the most effective targeted GBCA can be designed, synthesized, and analyzed, as well as presented new evidence into the impact functionalization strategies have on relaxometric values.
Author : Andre S. Merbach
Publisher : John Wiley & Sons
ISBN 13 : 1118503678
Total Pages : 514 pages
Book Rating : 4.1/5 (185 download)
Download or read book The Chemistry of Contrast Agents in Medical Magnetic Resonance Imaging written by Andre S. Merbach and published by John Wiley & Sons. This book was released on 2013-02-19 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic Resonance Imaging (MRI) is one of the most important tools in clinical diagnostics and biomedical research. The number of MRI scanners operating around the world is estimated to be approximately 20,000, and the development of contrast agents, currently used in about a third of the 50 million clinical MRI examinations performed every year, has largely contributed to this significant achievement. This completely revised and extended second edition: Includes new chapters on targeted, responsive, PARACEST and nanoparticle MRI contrast agents. Covers the basic chemistries, MR physics and the most important techniques used by chemists in the characterization of MRI agents from every angle from synthesis to safety considerations. Is written for all of those involved in the development and application of contrast agents in MRI. Presented in colour, it provides readers with true representation and easy interpretation of the images. A word from the Authors: Twelve years after the first edition published, we are convinced that the chemistry of MRI agents has a bright future. By assembling all important information on the design principles and functioning of magnetic resonance imaging probes, this book intends to be a useful tool for both experts and newcomers in the field. We hope that it helps inspire further work in order to create more efficient and specific imaging probes that will allow materializing the dream of seeing even deeper and better inside the living organisms. Reviews of the First Edition: "...attempts, for the first time, to review the whole spectrum of involved chemical disciplines in this technique..."—Journal of the American Chemical Society "...well balanced in its scope and attention to detail...a valuable addition to the library of MR scientists..."—NMR in Biomedicine
Author :
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (135 download)
Download or read book Designing Environmentally Responsible and Highly Effective Bioorthogonally Functionalized Chiral MRI Contrast Agents written by and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic resonance imaging (MRI) revolutionized diagnostic imaging and modernized the characterization of numerous diseases. The clinical success of MRI is in large part due to the employment of gadolinium-based contrast agents (GBCAs). Due to sensitivity limitations, GBCAs are indicated at markedly high dosages (~1 g Gd3+ per exam). The routine use of such large quantities of gadolinium poses significant health and environmental risks. There are growing concerns over the effects of dechelation of the metal in vivo and the possible effect of resulting gadolinium deposition. Concurrently, there is a rising awareness of gadolinium anomalies borne by GBCAs which undergo water treatment to be emitted into oceans, surface and potable waters. With increasing reports of gadolinium in the aquatic environment and negative effects on marine life, there are clear potential long-term health and environmental implications if this pollution is not properly addressed. To decrease gadolinium emission into the environment, improving GBCA efficacy to reduce dosage and devising a strategy for selective interception of GBCAs is essential. To address effectiveness, safety and environmental concerns, a series of new gadolinium chelates has been developed. Benzoate-substituted ligands were prepared through new diastereoselective and enantioselective synthetic routes to offer simple solutions toward the advancement of safer and more effective GBCAs. The effectiveness of DOTBA was characterized and found to behave similarly to previous work by our group, demonstrating an agent wherein tumbling, water exchange and hydration state are optimized in concert to achieve an efficacy over two times that of current clinically available GBCAs. Of significant note is the exceptional performance of DOTBA at clinical field strengths (1.5 T -- 3 T) where it is at least twice and up to three times as effective as current clinical agents. The high performance of DOTBA at clinical field strengths offers an agent which could decrease the dosage of Gd3+ by more than one-half, significantly reducing the consumption and emission of Gd3+. To further reduce the amount of Gd3+ pollution, we envisaged collection of the first urine pass post contrast-enhanced examination wherein nearly all of the dose is eliminated.
Author : Piper Julia Klemm
Publisher :
ISBN 13 :
Total Pages : 228 pages
Book Rating : 4.:/5 (839 download)
Download or read book Next Generation Magnetic Resonance Imaging Contrast Agents written by Piper Julia Klemm and published by . This book was released on 2012 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic resonance imaging (MRI) is one of the most powerful diagnostic techniques at the disposal of the medical community. Its success in the clinic, with 75 to 90 million scans performed worldwide annually, can be attributed in part to the use of injectable contrast agents to improve signal differentiation between healthy and pathological tissue. These contrast agents primarily use Gd(III) as the paramagnetic metal ion to induce contrast. With seven unpaired electrons, Gd(III) has the most paramagnetic character of any nonradioactive element. Aqueous Gd(III), however, is highly toxic; hence contrast agents use chelators to encapsulate the Gd(III) ion, which protects the patient from from the Gd(III) ion. While these chelators are necessary, they greatly decrease the relaxivity of the current commercial contrast agents. Commercial contrast agents are similar in that they are heteroatom chelators (N, O) and octadentate coordination, leaving only one open site for water coordination. Additionally, given their steric bulk, the water exchange mechanism with bulk solvent is a laboriously hindered dissociative mechanism. These factors contribute to the low efficiency of these Gd(III) complexes, as measured in relaxivity. Diagnostic scans typically inject 8-10 g of these complexes to achieve sufficient signal. Hydroxypyridinone (HOPO) chelators have emerged as a superior alternative to current commercial compounds. Using a tris(2-aminoethyl)amine (TREN) capping moiety, three bidentate HOPO chelators form a hexadentate ligand. These TREN-tris-HOPO ligands leave multiple open sites for water coordination and exhibit rapid water exchange with bulk solvent, due to their reduced steric bulk and associative exchange mechanism. These ligands use all-oxygen-donor chelators, capitalizing on the oxophilicity of Gd(III) to form highly stable complexes. From this superior family of chelators, a variety of approaches can be used to develop the next generation of MRI contrast agents. Increasing molecular weight and tumbling time has been a strategy for increasing relaxivity and efficiency of MRI contrast agents. Through macromolecular conjugation, relaxivity is readily increased; simultaneously, these macromolecules provide the potential for building multimodal and multifunctional diagnostic and therapeutic agents. The potential applications for this class of materials are further increased with the addition of targeting functionality. These agents must have the ability to be fully and rapidly excreted and have facile and uniform large-scale syntheses to be candidates for the clinic. The esteramide (EA) dendrimer is one such macromolecular platform. With eight sites for contrast agent conjugation, the esteramide dendrimer readily loads many distinct HOPO ligands with multiple lanthanides for multimodal imaging. With close to 40 kDa of polyethylene glycol units, the Gd-HOPO-EA macromolecular architecture is highly soluble and biocompatible. Furthermore, the ester core of the dendrimer is degradable under in vivo conditions, easing renal clearance with four smaller moieties. The superior properties of this system inspired investigation into a variety of other macromolecular systems. Porous silica mesoparticles provide a rigid architecture that is much larger than other macromolecules evaluated and can hold greater than 108 small molecule MRI contrast complexes. The surfaces of these particles are readily functionalized and suitable for conjugation with most small molecule MRI contrast agents. These structures use a nontoxic silica infrastructure and are excreted renally despite their large size, making them viable candidates for further in vitro and in vivo study. Gold nanoparticles (AuNP) as a solid-support system have the most potential for use as multifunctional diagnostic and therapeutic compounds. AuNP have been long used for enhancing computed tomography (CT) imaging and have recently emerged as a cancer therapeutic when their structure is irradiated. These compounds are readily synthesized in large scales and have loading sites that are close together to hold multi-tethered Gadolinium-HOPO systems for multifunctional imaging. Using a variety of macromolecules to capitalize on the structural relationship between relaxivity and size, per-Gd and per-macromolecule-Gd relaxivity have been increased dramatically at clinically and physiologically relevant conditions. These improvements show that the combination of carefully designed macromolecules with excellent HOPO chelators produces an ideal MRI contrast agent for the clinic of the future.
Author : Sophie Laurent
Publisher : Springer
ISBN 13 : 9811025290
Total Pages : 128 pages
Book Rating : 4.8/5 (11 download)
Download or read book MRI Contrast Agents written by Sophie Laurent and published by Springer. This book was released on 2016-11-03 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the multiple aspects of (i) preparation of the magnetic core, (ii) the stabilization with different coatings, (iii) the physico-chemical characterization and (iv) the vectorization to obtain specific nanosystems. Several bio-applications are also presented in this book. In the early days of Magnetic Resonance Imaging (MRI), paramagnetic ions were proposed as contrast agents to enhance the diagnostic quality of MR images. Since then, academic and industrial efforts have been devoted to the development of new and more efficient molecular, supramolecular and nanoparticular systems. Old concepts and theories, like paramagnetic relaxation, were revisited and exploited, leading to new scientific tracks. With their high relaxivity payload, the superparamagnetic nanoparticles are very appealing in the context of molecular imaging but challenges are still numerous: absence of toxicity, specificity, ability to cross the biological barriers, etc.
Author : Marco Essig
Publisher : Elsevier Health Sciences
ISBN 13 : 1455749788
Total Pages : 223 pages
Book Rating : 4.4/5 (557 download)
Download or read book MR Contrast Agents, An Issue of Magnetic Resonance Imaging Clinics written by Marco Essig and published by Elsevier Health Sciences. This book was released on 2012-11-28 with total page 223 pages. Available in PDF, EPUB and Kindle. Book excerpt: MRI contrast agents improve visibility of internal body structures. This issue offers a complete, practically focused review of the use of a variety of contrast agents for MR Imaging. A contrast agent not only must be safe, but also efficacious and cost-effective, and the articles in this issue address all three of these concerns and the uses of contrast agents for a variety of applications.
Author : Valérie C Pierre
Publisher : Royal Society of Chemistry
ISBN 13 : 1782624473
Total Pages : 612 pages
Book Rating : 4.7/5 (826 download)
Download or read book Contrast Agents for MRI written by Valérie C Pierre and published by Royal Society of Chemistry. This book was released on 2017-11-17 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt: As a practical reference guide for designing and performing experiments, this book focuses on the five most common classes of contrast agents for MRI namely gadolinium complexes, chemical exchange saturation transfer agents, iron oxide nanoparticles, manganese complexes and fluorine contrast agents. It describes how to characterize and evaluate them and for each class, a description of the theory behind their mechanisms is discussed briefly to orient the new reader. Detailed subchapters discuss the different physical chemistry methods used to characterize them in terms of their efficacy, safety and in vivo behavior. Important consideration is also given to the different physical properties that affect the performance of the contrast agents. The editors and contributors are at the forefront of research in the field of MRI contrast agents and this unique, cutting edge book is a timely addition to the literature in this area.
Author : Brian M. Dale
Publisher : John Wiley & Sons
ISBN 13 : 1119013038
Total Pages : 246 pages
Book Rating : 4.1/5 (19 download)
Download or read book MRI written by Brian M. Dale and published by John Wiley & Sons. This book was released on 2015-08-06 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: This fifth edition of the most accessible introduction to MRI principles and applications from renowned teachers in the field provides an understandable yet comprehensive update. Accessible introductory guide from renowned teachers in the field Provides a concise yet thorough introduction for MRI focusing on fundamental physics, pulse sequences, and clinical applications without presenting advanced math Takes a practical approach, including up-to-date protocols, and supports technical concepts with thorough explanations and illustrations Highlights sections that are directly relevant to radiology board exams Presents new information on the latest scan techniques and applications including 3 Tesla whole body scanners, safety issues, and the nephrotoxic effects of gadolinium-based contrast media
Author : Luca Frullano
Publisher :
ISBN 13 : 9789090178806
Total Pages : 174 pages
Book Rating : 4.1/5 (788 download)
Download or read book Towards Highly Efficient and Selective Contrast Agents for MRI written by Luca Frullano and published by . This book was released on 2004 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Gang Ho Lee
Publisher : Woodhead Publishing
ISBN 13 : 0081000693
Total Pages : 137 pages
Book Rating : 4.0/5 (81 download)
Download or read book Ultrasmall Lanthanide Oxide Nanoparticles for Biomedical Imaging and Therapy written by Gang Ho Lee and published by Woodhead Publishing. This book was released on 2014-11-22 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt: Most books discuss general and broad topics regarding molecular imagings. However, Ultrasmall Lanthanide Oxide Nanoparticles for Biomedical Imaging and Therapy, will mainly focus on lanthanide oxide nanoparticles for molecular imaging and therapeutics. Multi-modal imaging capabilities will discussed, along with up-converting FI by using lanthanide oxide nanoparticles. The synthesis will cover polyol synthesis of lanthanide oxide nanoparticles, Surface coatings with biocompatible and hydrophilic ligands will be discussed and TEM images and dynamic light scattering (DLS) patterns will be provided. Various techniques which are generally used in analyzing the synthesized surface coated nanoparticles will be explored and this section will also cover FT, IR analysis, XRD analysis, SQUID analysis, cytotoxicity measurements and proton relaxivity measurements. In vivo MR images, CT images, fluorescence images will be provided and Therapeutic application of gadolinium oxide nanoparticles will be discussed. Finally, future perpectives will be discussed. That is, present status and future works needed for clinical applications of lanthanide oxide nanoparticles to molecular imagings will be discussed. Synthesis will be discussed in detail General characterizations of nanoparticles before in vivo applications will be discussed The book will cover all possible applications of lanthanide oxide nanoparticles to molecular imagings such as MRI, CT, FI as well as therapeutics
Author : Alain R. Puente-Santiago
Publisher : Springer Nature
ISBN 13 : 303055502X
Total Pages : 255 pages
Book Rating : 4.0/5 (35 download)
Download or read book Surface-modified Nanobiomaterials for Electrochemical and Biomedicine Applications written by Alain R. Puente-Santiago and published by Springer Nature. This book was released on 2020-07-27 with total page 255 pages. Available in PDF, EPUB and Kindle. Book excerpt: The series Topics in Current Chemistry Collections presents critical reviews from the journal Topics in Current Chemistry organized in topical volumes. The scope of coverage is all areas of chemical science including the interfaces with related disciplines such as biology, medicine and materials science. The goal of each thematic volume is to give the non-specialist reader, whether in academia or industry, a comprehensive insight into an area where new research is emerging which is of interest to a larger scientific audience. Each review within the volume critically surveys one aspect of that topic and places it within the context of the volume as a whole. The most significant developments of the last 5 to 10 years are presented using selected examples to illustrate the principles discussed. The coverage is not intended to be an exhaustive summary of the field or include large quantities of data, but should rather be conceptual, concentrating on the methodological thinking that will allow the non-specialist reader to understand the information presented. Contributions also offer an outlook on potential future developments in the field.
Author : Ulrich Flogel
Publisher : CRC Press
ISBN 13 : 9814745324
Total Pages : 462 pages
Book Rating : 4.8/5 (147 download)
Download or read book Fluorine Magnetic Resonance Imaging written by Ulrich Flogel and published by CRC Press. This book was released on 2016-10-26 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past decade, fluorine (19F) magnetic resonance imaging (MRI) has garnered significant scientific interest in the biomedical research community owing to the unique properties of fluorinated materials and the 19F nucleus. Fluorine has an intrinsically sensitive nucleus for MRI. There is negligible endogenous 19F in the body and thus there is no background signal. Fluorine-containing compounds are ideal tracer labels for a wide variety of MRI applications. Moreover, the chemical shift and nuclear relaxation rate can be made responsive to physiology via creative molecular design. This book is an interdisciplinary compendium that details cutting-edge science and medical research in the emerging field of 19F MRI. Edited by Ulrich Flögel and Eric Ahrens, two prominent MRI researchers, this book will appeal to investigators involved in MRI, biomedicine, immunology, pharmacology, probe chemistry, and imaging physics.
Author : National Research Council
Publisher : National Academies Press
ISBN 13 : 030916463X
Total Pages : 222 pages
Book Rating : 4.3/5 (91 download)
Download or read book Visualizing Chemistry written by National Research Council and published by National Academies Press. This book was released on 2006-06-01 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientists and engineers have long relied on the power of imaging techniques to help see objects invisible to the naked eye, and thus, to advance scientific knowledge. These experts are constantly pushing the limits of technology in pursuit of chemical imagingâ€"the ability to visualize molecular structures and chemical composition in time and space as actual events unfoldâ€"from the smallest dimension of a biological system to the widest expanse of a distant galaxy. Chemical imaging has a variety of applications for almost every facet of our daily lives, ranging from medical diagnosis and treatment to the study and design of material properties in new products. In addition to highlighting advances in chemical imaging that could have the greatest impact on critical problems in science and technology, Visualizing Chemistry reviews the current state of chemical imaging technology, identifies promising future developments and their applications, and suggests a research and educational agenda to enable breakthrough improvements.
Author : Frederick A. Villamena
Publisher : Elsevier
ISBN 13 : 012420080X
Total Pages : 342 pages
Book Rating : 4.1/5 (242 download)
Download or read book Reactive Species Detection in Biology written by Frederick A. Villamena and published by Elsevier. This book was released on 2016-10-23 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reactive Species Detection in Biology: From Fluorescence to Electron Paramagnetic Resonance Spectroscopy discusses the reactive oxygen species that have been implicated in the pathogenesis of various diseases, presenting theories, chemistries, methodologies, and various applications for the detection of reactive species in biological systems, both in-vitro and in-vivo. Techniques covered include fluorescence, high performance chromatography, mass spectrometry, immunochemistry, and electron paramagnetic resonance spectroscopy. Probe design and development are also reviewed in order to advance new approaches in radical detection through synthesis, computations, or experimental applications. Reviews all current advances in radical detection Emphasizes chemical structures and reaction schemes fundamental to radical detection and identification Describes the uses, advantages, and disadvantages of various probe designs Examines new approaches to radical probe development
