Sensitivity enhancement by exchange mediated magnetization transfer of the xenon biosensor signal

García, Sandra G.; Chavez, Lana; Lowery, Thomas J.; Han, Songi; Wemmer, David E.; Pines, Alexander

doi:10.1016/j.jmr.2006.09.010

Cited by 29 publications

(26 citation statements)

References 20 publications

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“…Several studies reported CEST imaging of biological molecules such as glycogen,68 an endogenous lysine-rich protein (LRP) as a reporter gene,69 and proteins and peptides 70. CEST imaging was also applied to MRI of a hyperpolarized Xe noble gas 71, 72. These CEST probes are classified as DIACEST because of their diamagnetic nature 73…”

Section: Multifunctional Nanomedicinementioning

confidence: 99%

Polymeric nanomedicine for cancer MR imaging and drug delivery

2009

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Multifunctional nanomedicine is emerging as a highly integrated platform that allows for molecular diagnosis, targeted drug delivery, and simultaneous monitoring and treatment of cancer. Advances in polymer and materials science are critical for the successful development of these multi-component nanocomposites in one particulate system with such a small size confinement (<200 nm). Currently, several nanoscopic therapeutic and diagnostic systems have been translated into clinical practices. In this feature article, we will provide an up-to-date review on the development and biomedical applications of nanocomposite materials for cancer diagnosis and therapy. Overview of each functional component, i.e. polymer carriers, MR imaging agents, and therapeutic drugs will be presented. Integration of different functional components will be illustrated in several highlighted examples to demonstrate the synergy of the multifunctional nanomedicine design.

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Section: Multifunctional Nanomedicinementioning

confidence: 99%

Polymeric nanomedicine for cancer MR imaging and drug delivery

2009

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“…While detecting a reduction in water signal produced by saturation pulse(s) is still the predominant method for observing CEST contrast, several alternative methods have been also reported (73-77), and more may be presented in the near future. Therefore, to be more general, CEST is defined as a type of MRI contrast that is created by applying pulses to exchangeable protons and observing the subsequent alteration in water magnetization.…”

Section: Introductionmentioning

confidence: 99%

“…The FLEX and Exchange Signal Averaging (ESA) sequences are fundamentally different from saturation transfer in that a modulation in water signal is imparted based on an evolution time (t evol ) which is similar to the indirect dimensions in multi-dimensional NMR experiments (73,77,100). These methods aren't technically CEST methods, as saturation transfer is not employed, however they fall under the CEST imaging umbrella as they are methods which allow the collection of images with the contrast in these images dependent on chemical exchange.…”

Section: Introductionmentioning

confidence: 99%

Nuts and bolts of chemical exchange saturation transfer MRI

et al. 2013

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Chemical Exchange Saturation Transfer (CEST) has emerged as a novel MRI contrast mechanism that is well suited for molecular imaging studies. This new mechanism can be used to detect small amounts of contrast agent through saturation of rapidly exchanging protons on these agents, allowing a wide range of applications. CEST technology has a number of indispensable features, such as the possibility of simultaneous detection of multiple “colors” of agents and detecting changes in their environment (e.g. pH, metabolites, etc) through MR contrast. Currently a large number of new imaging schemes and techniques have been developed to improve the temporal resolution and specificity and to correct the influence of B0 and B1 inhomogeneities. In this review, the techniques developed over the last decade have been summarized with the different imaging strategies and post-processing methods discussed from a practical point of view including describing their relative merits for detecting CEST agents. The goal of the present work is to provide the reader with a fundamental understanding of the techniques developed, and to provide guidance to help refine future applications of this technology. This review is organized into three main sections: Basics of CEST Contrast, Implementation, Post-Processing, and also includes a brief Introduction section and Summary. The Basics of CEST Contrast section contains a description of the relevant background theory for saturation transfer and frequency labeled transfer, and a brief discussion of methods to determine exchange rates. The Implementation section contains a description of the practical considerations in conducting CEST MRI studies, including choice of magnetic field, pulse sequence, saturation pulse, imaging scheme, and strategies to separate MT and CEST. The Post-Processing section contains a description of the typical image processing employed for B0/B1 correction, Z-spectral interpolation, frequency selective detection, and improving CEST contrast maps.

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“…In the direct detection methods, fast repetition of spectrallyselective pulses around the small reservoir resonance frequency (and detection after each pulse) uses the chemical exchange between the two environments to gradually increase the signal-to-noise ratio. 56,57 The repetition rhythm is chosen according to the exchange rate of xenon between the two environments.…”

Section: Methodsmentioning

confidence: 99%

¹²⁹Xe NMR-based sensors: biological applications and recent methods

Mari

Berthault

2017

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aXenon is a first-rate sensor of biological events, due to its large polarizable electron cloud inducing significant modification of NMR parameters through slight changes in its local environment. The use of xenon as a sensor is of increasing interest for sensitive magnetic resonance imaging, since its signal can be enhanced by several orders of magnitude, mainly by spinexchange optical pumping. Furthermore xenon can be vectorized toward targets of interest by using functionalized host systems, enabling their detection at subnanomolar concentrations. Associated with a new generation of detection methods this gives rise to a powerful molecular imaging approach, where xenon can be delivered on purpose several times after introduction of the functionalized host system. IntroductionFrom simple photograph of the inside of the human body providing information on bone structure or form and abnormalities of various organs, molecular imaging now offers a dynamic view of biological processes occurring locally, witnessing for instance the presence of infectious cells or metabolic deregulations. The development of powerful imaging techniques is the key to early diagnosis of disease, best follow-up treatments and also biomedical research tools. These techniques developed particularly in the 21th century form part of the molecular imaging concept. Magnetic resonance imaging (MRI) is a good compromise to achieve molecular imaging in vivo in real time without any perturbative radiation. The major advantages of MRI are its potential high spatial resolution (25-100 µm), its low invasiveness, its harmlessness and the excellent tissue contrast it can provide. In this context, MRI complements and sometimes overruns other molecular imaging approaches by enabling monitoring of events at the cellular or even subcellular level. However, classical implementation of this technique suffers from low sensitivity due to the very low population differences between nuclear spin energy levels at Boltzmann equilibrium. Hyperpolarization techniques 1 that transiently increase the nuclear spin polarization of a very dilute agent by several orders of magnitude circumvent the MRI sensitivity problem. Among the species that can be spinhyperpolarized, xenon is of high interest, due to its exogenous nature (leading to the absence of background signal) and the fact that it can act as a spy of biological events without interfering with them. Moreover, it can be endlessly reloaded and simply removed from the sample since it is a gas at ambient temperature and pressure. Finally, owing to the high deformability of its large electron cloud xenon is deeply sensitive to its local environment and constitutes a perfect probe for various biological interactions. Soluble in most biological fluids, xenon can cross the plasma membrane in a few tens of milliseconds without losing its hyperpolarization. 2The initial applications of hyperpolarized xenon in biology were the anatomical imaging of the lung 3 and the investigation of hydrophobic binding pockets in proteins ...

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Sensitivity enhancement by exchange mediated magnetization transfer of the xenon biosensor signal

Cited by 29 publications

References 20 publications

Polymeric nanomedicine for cancer MR imaging and drug delivery

Polymeric nanomedicine for cancer MR imaging and drug delivery

Nuts and bolts of chemical exchange saturation transfer MRI

¹²⁹Xe NMR-based sensors: biological applications and recent methods

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Sensitivity enhancement by exchange mediated magnetization transfer of the xenon biosensor signal

Cited by 29 publications

References 20 publications

Polymeric nanomedicine for cancer MR imaging and drug delivery

Polymeric nanomedicine for cancer MR imaging and drug delivery

Nuts and bolts of chemical exchange saturation transfer MRI

129Xe NMR-based sensors: biological applications and recent methods

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¹²⁹Xe NMR-based sensors: biological applications and recent methods