Mapping of amide, amine, and aliphatic peaks in the CEST spectra of murine xenografts at 7 T

Desmond, Kimberly L.; Moosvi, Firas; Stanisz, Greg J.

doi:10.1002/mrm.24822

Cited by 178 publications

(266 citation statements)

References 41 publications

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“…Three recent dedicated CEST workshops (3rd, 4th, and 5th international CEST workshops in Annapolis, 2012, Torino, 2014, and Philadelphia 2016) drew about 90-200 registrants. The last decade has shown major developments for paraCEST agents, 14,15,20,89,90,119,[135][136][137][138][139][140][141][142][143][144][145][146][147][148] diaCEST agents, 12,13,17,42,43,68,72,88,102,116,125,128,[149][150][151][152][153][154][155][156][157][158][159][160] and even hyperpolarized (hyperCEST) agents. 161,162 This is not surprising in view of the number of potential applications including pH imaging, metabolite detection, ion detection, cellular protein and peptide imaging, cell labeling, temperature i...…”

Section: Potential and Clinical Translation Of Cest Methodsmentioning

confidence: 99%

“…It is no doubt clear from the previous sections that there is a lot of ongoing effort by CEST researchers to analyze the different contributions to the Z-spectrum and edit these in or out 73,120,[125][126][127][128][129][130][131] to provide more specific measurements of individual spectral components. The reason of course is to quantify endogenous and contrast-agent contributions as well as other parameters in the CEST equations that can provide information regarding physiological processes in vivo.…”

Section: Quantification Of Cest-related Parametersmentioning

confidence: 99%

“…Subsequently, APT was used to detect pH changes during early ischemia (based on the pH dependence of the amide proton exchange rate) 43,62,88 and increases in the mobile protein/peptide content of brain tumor tissue. 42,165 In these studies, CEST effects were assessed using MTR asym analysis and, due to contamination by other transfer processes, 21,42,43,53,72,102,[125][126][127][128]130,131,166 it is most appropriate to refer to the contrast achieved as APTw. In studies of cancer in the brain, APTw MRI is showing promise for (i) separating high-grade tumors from low-grade tumors and edema; 42,112,167 (ii) distinguishing recurrent tumor from treatment necrosis; 159 and (iii) detecting early response to treatment.…”

Section: Amide Proton Transfer-weighted (Aptw) Mrimentioning

confidence: 99%

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Proton Chemical Exchange Saturation Transfer (CEST) MRS and MRI

Zijl

Sehgal

2016

eMagRes

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Proton magnetic resonance spectroscopy ( 1 H MRS) of biological systems has higher specificity than MRI because resonances of multiple metabolites can be distinguished, reflecting chemistry and physiology in situ. Unfortunately, this approach has very low sensitivity as the metabolites are typically at millimolar concentrations compared to the molar signal strength of water-based MRI. As a consequence, even though 1 H MRS is a powerful and common research tool, its inroad into daily clinical practice has been limited. Until very recently, 1 H MRS applications have focused on the resonances upfield (i.e., at lower frequency) of the water resonance. This article deals with protons that are generally not observed in a typical water-suppressed spectrum, namely, the exchangeable protons found predominantly downfield from water. These can usually be detected by MRS only if the transfer of water proton saturation (established during water suppression) is not a confounding factor, or by using water exchange (WEX) spectroscopy, in which RF labeling of the water protons is transferred to the exchangeable protons and subsequently detected. More importantly, it has recently become clear that the presence of such exchangeable protons on low concentration solute molecules can be detected via the water signal by RF labeling of these protons and subsequent transfer of this label to water protons. This process, leading to saturation of the water signal and enhancement of the effect through repeated exchange, can be used for the imaging of metabolite signals or exchangeable-proton-based contrast agents with enhanced sensitivity. This has given rise to the field of chemical exchange saturation transfer (CEST) MRI, which has greatly increased the potential for translating spectroscopic methods to the clinic. Examples include the measurement of pH, temperature, and enzyme activity as well as detection of cellular metabolites, ions, and proteins and peptides. In addition, bio-organic compounds can now be used for contrast agents, cell and nanoparticle labeling, and reporter genes.

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Section: Potential and Clinical Translation Of Cest Methodsmentioning

confidence: 99%

Section: Quantification Of Cest-related Parametersmentioning

confidence: 99%

Section: Amide Proton Transfer-weighted (Aptw) Mrimentioning

confidence: 99%

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Proton Chemical Exchange Saturation Transfer (CEST) MRS and MRI

Zijl

Sehgal

2016

eMagRes

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“…The six pool protons are defined in the initial offset frequency values as water at 0 ppm, amide at 3.5 ppm, amine at 3.0 ppm, hydroxyl at 0.9 ppm, the nuclear overhauser effect (NOE) at -3.5 ppm, and the magnetization transfer (MT) at -1.5 ppm. 8,[30][31][32] The problems with this Lorentizian fitting are that the fitted results are strongly depended on the initial values and the calculation takes relatively long time compared to that to obtain the asymmetry value.…”

Section: )mentioning

confidence: 99%

Physical Modeling of Chemical Exchange Saturation Transfer Imaging

Jahng

2017

Prog Med Phys

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Chemical Exchange Saturation Transfer (CEST) imaging is a method to detect solutes based on the chemical exchange of mobile protons with water. The solute protons exchange with three different patterns, which are fast, slow, and intermediate rates. The CEST contrast can be obtained from the exchangeable protons, which are hydroxyl protons, amine protons, and amide protons. The CEST MR imaging is useful to evaluate tumors, strokes, and other diseases. The purpose of this study is to review the mathematical model for CEST imaging and for measurement of the chemical exchange rate, and to measure the chemical exchange rate using a 3T MRI system on several amino acids. We reviewed the mathematical models for the proton exchange. Several physical models are proposed to demonstrate a two-pool, three-pool, and four-pool models. The CEST signals are also evaluated by taking account of the exchange rate, pH and the saturation efficiency. Although researchers have used most commonly in the calculation of CEST asymmetry, a quantitative analysis is also developed by using Lorentzian fitting. The chemical exchange rate was measured in the phantoms made of asparagine (Asn), glutamate (Glu), γ-aminobutyric acid (GABA), glycine (Gly), and myoinositol (MI). The experiment was performed at a 3T human MRI system with three different acidity conditions (pH 5.6, 6.2, and 7.4) at a concentration of 50 mM. To identify the chemical exchange rate, the "lsqcurvefit" built-in function in MATLAB was used to fit the pseudofirst exchange rate model. The pseudo-first exchange rate of Asn and Gly was increased with decreasing acidity. In the case of GABA, the largest result was observed at pH 6.2. For Glu, the results at pH 5.6 and 6.2 did not show a significant difference, and the results at pH 7.4 were almost zero. For MI, there was no significant difference at pH 5.6 or 7.4, however, the results at pH 6.2 were smaller than at the other pH values. For the experiment at 3T, we were only able to apply 1 s as the maximum saturation duration due to the limitations of the MRI system. The measurement of the chemical exchange rate was limited in a clinical 3T MRI system because of a hardware limitation.

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“…So ist beispielsweise durch Bildgebung des Amid-, Amin-und Aliphat-Signals (aaaCEST) eine nichtinvasive Differenzierung von apoptotischen und nekrotischen bzw. apoptotischen und/oder nekrotischen Tumorarealen und aktivem Tumor mög-lich [41]. Nach intravenöser Applikation von Glukose kann mit CEST-(glucoCEST-)ähnlicher FDG-PET eine nichtinvasive Evaluation des Gewebsglukosestoffwechsels vorgenommen werden [42].…”

Section: Chemical-exchange-saturationtransfer(cest)-bildgebungunclassified

Multiparametrische und molekulare Bildgebung von Brusttumoren mit MRT und PET‑MRT

et al. 2016

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Hintergrund MRT der BrustQuantitative KM-MRT [6] erstmals die klinische Anwendbarkeit der bilateralen KM-MRT der Brust bei 7 T an Patientinnen mit Brusttumoren. Die Autoren der Studie kamen zu dem Schluss, dass die bilaterale KM-MRT der Brust bei 7 T klinisch anwendbar ist und eine Brustkrebsdiagnostik mit hoher diagnostischer Genauigkeit (96,6 %), einem ausgezeichnetem Interrateragreement und einer exzellenten Bildqualität ermöglicht. Gruber et al. [19] verglichen Bildqualität, Kontrastmittelanfärbever-halten und diagnostische Genauigkeit der bilateralen KM-MRT der Brust bei 7 und 3 T im selben Patientinnenkollektiv. Im Vergleich zu 3 T war eine signifikant bessere räumliche und zeitliche Auflösung möglich und es konnte eine exzellente Sensitivität und gute Spezifität von 100 und 91,67 % in der Brustkrebsdiagnostik erzielt werden. Diffusionsgewichtete BildgebungMit diffusionsgewichteten MR-Sequenzen("diffusion-weighted imaging", DWI) wird die zufällige Bewegung von Wassermolekülen nichtinvasiv im Gewebe gemessen. Die gemessene Diffusivität des untersuchten Gewebes stellt so einen Surrogatmarker für die Mikrostruktur und Zelldichte dar und wird durch den "apparent diffusion coefficient" (ADC)

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Mapping of amide, amine, and aliphatic peaks in the CEST spectra of murine xenografts at 7 T

Abstract: CEST contrast (particularly the amine peak amplitude) performed especially well in distinguishing areas of apoptosis and/or necrosis from actively progressing tumor, as validated by histology.

Cited by 178 publications

References 41 publications

Proton Chemical Exchange Saturation Transfer (CEST) MRS and MRI

Proton Chemical Exchange Saturation Transfer (CEST) MRS and MRI

Physical Modeling of Chemical Exchange Saturation Transfer Imaging

Multiparametrische und molekulare Bildgebung von Brusttumoren mit MRT und PET‑MRT

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