Read by QxMD icon Read

Chemical exchange saturation transfer

Xuanqi Xiong, Zhengwei Zhou, Matteo Figini, Junjie Shangguan, Zhuoli Zhang, Wei Chen
Objective: To quantitatively evaluate lumbar disc degeneration with recently-developed quantitative magnetic resonance imaging (MRI) techniques. A series of MRI parameters, including T2*, T1rho relaxation time, apparent diffusion coefficient and gagCEST, were compared and correlated with the Pfirrmann semi-quantitative classification of lumbar intervertebral disc degeneration; the most accurate and relevant MRI parameters of lumbar disc degeneration were identified. Materials and Methods: Thirty-seven subjects (age range, 18-74 years) with non-specific low back pain (LBP) for more than 6 months were enrolled...
2018: American Journal of Translational Research
Sangeeta Ray Banerjee, Xiaolei Song, Xing Yang, Il Minn, Ala Lisok, Yanrong Chen, Martin G Pomper, Peter C M van Zijl, Michael McMahon, Jian Chen
Chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) is an innovative molecular imaging technique in which contrast agents are labeled by saturating their exchangeable protons spins by radio frequency irradiation. Salicylic acid and its analogues are a promising class of highly sensitive, diamagnetic CEST agents. We synthesized polymeric agents grafted with salicylic acid moieties and a known high-affinity ligand targeting prostate-specific membrane antigen (PSMA) in a ~10:1 molar ratio to provide sufficient MRI sensitivity and receptor specificity...
March 5, 2018: Chemistry: a European Journal
Eleni Demetriou, Mohamed Tachrount, Moritz Zaiss, Karin Shmueli, Xavier Golay
PURPOSE: To develop a new MRI technique to rapidly measure exchange rates in CEST MRI. METHODS: A novel pulse sequence for measuring chemical exchange rates through a progressive saturation recovery process, called PRO-QUEST (progressive saturation for quantifying exchange rates using saturation times), has been developed. Using this method, the water magnetization is sampled under non-steady-state conditions, and off-resonance saturation is interleaved with the acquisition of images obtained through a Look-Locker type of acquisition...
March 5, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Kyle M Jones, Carol A Stuehm, Charles C Hsu, Phillip H Kuo, Mark D Pagel, Edward A Randtke
Performing chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) in lung tissue is difficult because of motion artifacts. We, therefore, developed a CEST MRI acquisition and analysis method that performs retrospective respiration gating. Our method used an acquisition scheme with a short 200-millisecond saturation pulse that can accommodate the timing of the breathing cycle, and with saturation applied at frequencies in 0.03-ppm intervals. The Fourier transform of each image was used to calculate the difference in phase angle between adjacent pixels in the longitudinal direction of the respiratory motion...
December 2017: Tomography: a Journal for Imaging Research
N A da Silva, P Lohmann, J Fairney, A W Magill, A-M Oros Peusquens, C-H Choi, R Stirnberg, G Stoffels, N Galldiks, X Golay, K-J Langen, N Jon Shah
PURPOSE: PET using radiolabelled amino acids has become a promising tool in the diagnostics of gliomas and brain metastasis. Current research is focused on the evaluation of amide proton transfer (APT) chemical exchange saturation transfer (CEST) MR imaging for brain tumour imaging. In this hybrid MR-PET study, brain tumours were compared using 3D data derived from APT-CEST MRI and amino acid PET using O-(2-18 F-fluoroethyl)-L-tyrosine (18 F-FET). METHODS: Eight patients with gliomas were investigated simultaneously with18 F-FET PET and APT-CEST MRI using a 3-T MR-BrainPET scanner...
February 24, 2018: European Journal of Nuclear Medicine and Molecular Imaging
Daniel F Gochberg, Mark D Does, Zhongliang Zu, Christopher L Lankford
Chemical exchange saturation transfer (CEST) is an imaging method based on magnetization exchange between solutes and water. This exchange generates changes in the measured signal after off-resonance radiofrequency irradiation. Although the analytic solution for CEST with continuous wave (CW) irradiation has been determined, most studies are performed using pulsed irradiation. In this work, we derive an analytic solution for the CEST signal after pulsed irradiation that includes both short-time rotation effects and long-time saturation effects in a two-pool system corresponding to water and a low-concentration exchanging solute pool...
February 20, 2018: NMR in Biomedicine
Zhongliang Zu, Aqeela Afzal, Hua Li, Jingping Xie, John C Gore
We have previously reported that the dispersion of spin-lattice relaxation rates in the rotating frame (R1ρ ) of tissue water protons at high field can be dominated by chemical exchange contributions. Ischemia in brain causes changes in tissue pH, which in turn may affect proton exchange rates. Amide proton transfer (APT, a form of chemical exchange saturation transfer) has been shown to be sensitive to chemical exchange rates and able to detect pH changes non-invasively following ischemic stroke. However, the specificity of APT to pH changes is decreased because of the influence of several other factors that affect magnetization transfer...
February 9, 2018: NMR in Biomedicine
Samira M Abozeid, Eric M Snyder, Timothy Y Tittiris, Charles M Steuerwald, Alexander Y Nazarenko, Janet R Morrow
High-spin Co(II) complexes are promising for development as paraCEST agents (paraCEST = paramagnetic chemical exchange saturation transfer) for magnetic resonance imaging applications. The first examples of Co(II) paraCEST agents with bound water ligands are presented here. Four Co(II) macrocyclic complexes based on 1,4,7-triazacyclononane and containing either pendent alcohol or pendent amide groups were prepared. Two of the macrocycles encapsulate the Co(II) and contain no water ligands as shown by X-ray crystallographic studies, and two complexes have macrocycles with only five ligand donor groups to leave an open coordination site for bound water...
February 7, 2018: Inorganic Chemistry
Marianne E Burnett, Bokola Adebesin, Alexander M Funk, Zoltan Kovacs, A Dean Sherry, Levi A Ekanger, Matthew J Allen, Kayla N Green, S James Ratnakar
The Eu3+/2+ redox couple provides a convenient design platform for responsive pO2 sensors for magnetic resonance imaging (MRI). Specifically the Eu2+ ion provides T1w contrast enhancement under hypoxic conditions in tissues, whereas, under normoxia, the Eu3+ ion can produce contrast from chemical exchange saturation transfer in MRI. The oxidative stability of the Eu3+/2+ redox couple for a series of tetraaza macrocyclic complexes was investigated in this work using cyclic voltammetry. A series of Eu-containing cyclen-based macrocyclic complexes revealed positive shifts in the Eu3+/2+ redox potentials with each replacement of a carboxylate coordinating arm of the ligand scaffold with glycinamide pendant arms...
November 24, 2017: European Journal of Inorganic Chemistry
Sander Brinkhof, Razmara Nizak, Vitaliy Khlebnikov, Jeanine J Prompers, Dennis W J Klomp, Daniel B F Saris
OBJECTIVES: The purpose was to implement a fast 3D glycosaminoglycan Chemical Exchange Saturation Transfer (gagCEST) sequence at 7 T, test stability and reproducibility in cartilage in the knee in healthy volunteers, and evaluate clinical applicability in cartilage repair patients. METHODS: Experiments were carried out on a 7-T scanner using a volume transmit coil and a 32-channel receiver wrap-around knee coil. The 3D gagCEST measurement had an acquisition time of 7 min...
January 30, 2018: European Radiology
Ulrich Flögel, Anke Schlüter, Christoph Jacoby, Sebastian Temme, J Paul Banga, Anja Eckstein, Jürgen Schrader, Utta Berchner-Pfannschmidt
PURPOSE: To evaluate key molecular and cellular features of Graves orbitopathy (GO) by simultaneous monitoring of alterations in morphology, inflammatory patterns, and tissue remodeling. METHODS: To this end, we utilized a murine model of GO induced by immunization with a human thyroid-stimulating hormone receptor A-subunit plasmid. Altogether, 52 mice were used: 27 GOs and 25 controls (Ctrl) immunized with β-galactasidose plasmid. From these, 17 GO and 12 Ctrl mice were subjected to multimodal MRI at 9...
January 27, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Moritz Zaiss, Philipp Ehses, Klaus Scheffler
Gradient echo (GRE)-based acquisition provides a robust readout method for chemical exchange saturation transfer (CEST) at ultrahigh field (UHF). To develop a snapshot-CEST approach, the transient GRE signal and point spread function were investigated in detail, leading to optimized measurement parameters and reordering schemes for fast and robust volumetric CEST imaging. Simulation of the transient GRE signal was used to determine the optimal sequence parameters and the maximum feasible number of k-space lines...
January 26, 2018: NMR in Biomedicine
Valérie C Pierre, Sarah M Harris, Sylvie L Pailloux
Magnetic resonance imaging (MRI) has emerged over the years as one of the preferred modalities for medical diagnostic and biomedical research. It has the advantage over other imaging modalities such as positron emission tomography and X-ray of affording high resolution three-dimensional images of the body without using harmful radiation. The use of contrast agents has further expanded this technique by increasing the contrast between regions where they accumulate and background tissues. As MRI most often measures the relaxation rate of water throughout the body, contrast agents function by modulating the intensity of the water signal either via improved relaxation or via saturation transfer to selected exchangeable proton...
January 22, 2018: Accounts of Chemical Research
Tairan Yuwen, Lewis E Kay
Chemical exchange saturation transfer (CEST) experiments are becoming increasingly popular for investigating biomolecular exchange dynamics with rates on the order of approximately 50-500 s-1 and a rich toolkit of different methods has emerged over the past few years. Typically, experiments are based on the evolution of longitudinal magnetization, or in some cases two-spin order, during a fixed CEST relaxation delay, with the same class of magnetization prepared at the start and selected at end of the CEST period...
January 19, 2018: Journal of Biomolecular NMR
Lalit Deshmukh, Vitali Tugarinov, Daniel H Appella, G Marius Clore
HIV-1 nucleocapsid (NCp7) is a two Cys2HisCys zinc knuckle (N-Zn and C-Zn) protein that plays a key role in viral replication. Here we characterize NCp7 conformational dynamics by NMR relaxation dispersion and chemical exchange saturation transfer measurements. While the N-Zn knuckle is conformationally stable, the C-Zn knuckle interconverts on the millisecond time scale between the major state, in which the zinc is coordinated by three cysteines and a histidine, and two folded minor species (with populations around 1%) in which one of the coordination bonds (Cys413-S---Zn or His421-N2---Zn) is hydrolysed...
January 18, 2018: Angewandte Chemie
Pedro Ramos-Cabrer, Daniel Padro
Stroke consists of the loss of cerebral functions resulting from the interruption of blood supply to a region of the brain, and represents the second cause of death and the leading cause of major disability in adults in Europe. Stroke is a very active field of research at preclinical and clinical levels, and Magnetic Resonance Imaging (MRI) is one of the most powerful tools that scientist and clinicians have for the study of the onset, evolution and consequences of this devastating disease, as well as for the monitoring of the success of available treatments, or for the development of novel therapeutic strategies...
2018: Methods in Molecular Biology
N Lokesh, Andreas Seegerer, Johnny Hioe, Ruth M Gschwind
The low sensitivity of NMR and transient key intermediates below detection limit are the central problems studying reaction mechanisms by NMR. Sensitivity can be enhanced by hyperpolarization techniques such as dynamic nuclear polarization or the incorporation/interaction of special hyperpolarized molecules. However, all of these techniques require special equipment, are restricted to selective reactions or undesirably influence the reaction pathways. Here, we apply the Chemical Exchange Saturation Transfer (CEST) technique for the first time to NMR detect and characterize previously unobserved transient reaction intermediates in organocatalysis...
January 16, 2018: Journal of the American Chemical Society
Tsang-Wei Tu, Wael G Ibrahim, Neekita Jikaria, Jeeva P Munasinghe, Jaclyn A Witko, Dima A Hammoud, Joseph A Frank
Metabolic abnormalities are commonly observed in traumatic brain injury (TBI) patients exhibiting long-term neurological deficits. This study investigated the feasibility and reproducibility of using chemical exchange saturation transfer (CEST) MRI to detect cerebral metabolic depression in experimental TBI. Phantom and in vivo CEST experiments were conducted at 9.4 Tesla to optimize the selective saturation for enhancing the endogenous contrast-weighting of the proton exchanges over the range of glucose proton chemical shifts (glucoCEST) in the resting rat brain...
January 12, 2018: Scientific Reports
Shu Zhang, Stephen Seiler, Xinzeng Wang, Ananth J Madhuranthakam, Jochen Keupp, Emily E Knippa, Robert E Lenkinski, Elena Vinogradov
PURPOSE: Chemical exchange saturation transfer (CEST) MRI for breast lesion characterization is promising. However, artifacts are prone to develop in breast CEST imaging as a result of strong lipid signals. The aims of the study are (i) to develop and validate the CEST-Dixon imaging sequence for simultaneous water-fat separation and B0 mapping; and (ii) use the CEST-Dixon method to characterize suspicious lesions in patients undergoing percutaneous biopsy. METHODS: The gradient-echo multi-echo Dixon acquisition is used to create fat-free CEST and B0 maps...
January 10, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Jiaxuan Zhang, Wenzhen Zhu, Rongwen Tain, Xiaohong Joe Zhou, Kejia Cai
PURPOSE: The purpose of the study is to demonstrate the value of quantitative amide proton transfer (APT) imaging for differentiating glioma grades and detecting tumor proliferation. PROCEDURES: This study included 32 subjects with 16 low-grade gliomas (LGG) and 16 high-grade gliomas (HGG) confirmed by histopathology. Chemical exchange saturation transfer (CEST) magnetic resonance imaging with APT weighting was performed on a 3 T scanner. After B0 correction, Z-spectra were fitted with Lorentzian functions corresponding to the upfield semi-solid magnetization transfer and nuclear overhauser enhancement (MT&NOE) effect, the direct saturation (DS) effect, and the downfield APT effect centered at around - 1...
January 8, 2018: Molecular Imaging and Biology: MIB: the Official Publication of the Academy of Molecular Imaging
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"