scholarly journals Presaturation Power Adjusted Pulsed CEST: A Method to Increase Independence of Target CEST Signals

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Kazufumi Kikuchi ◽  
Keisuke Ishimatsu ◽  
Shanrong Zhang ◽  
Ivan E. Dimitrov ◽  
Hiroshi Honda ◽  
...  
Keyword(s):  
Exchange Rates ◽  
Chemical Exchange ◽  
Renal Medulla ◽  
Chemical Exchange Saturation Transfer ◽  
Amide Proton ◽  
Saturation Transfer ◽  
Cest Imaging ◽  
Concentration Changes

Chemical exchange saturation transfer (CEST) imaging has been demonstrated to discuss the concentration changes of amide proton, glutamate, creatine, or glucose measured at 3.5, 3.0, 2.0, and 1.0–1.2 ppm. However, these peaks in z-spectra are quite broad and overlap with each other, and thus, the independence of a CEST signal on any specific metabolite is still open to question. Here, we described whether there was interference among the CEST signals and how these CEST signals behave when the power of the presaturation pulse was changed. Based on these results, further experiments were designed to investigate a method to increase the independence of the CEST signal in both phantoms and animals. The result illustrates a clear interference among CEST signals. A presaturation power adjusted pulsed- (PPAP-) CEST method which was designed based on the exchange rates of the metabolites can be used to remove contributions from other exchanging species in the same sample. Further, the method was shown to improve the independence of the glutamate signal in vivo in the renal medulla in mice. The PPAP-CEST method has the potential to increase the independence of any target CEST signals in vivo by choosing the appropriate combination of pulse amplitudes and durations.

scholarly journals Novel nanomedicine with a chemical-exchange saturation transfer effect for breast cancer treatment in vivo

2019 ◽  
Vol 17 (1) ◽  
Author(s):  
Yanlong Jia ◽  
Chaochao Wang ◽  
Jiehua Zheng ◽  
Guisen Lin ◽  
Dalong Ni ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Treatment ◽  
Chemical Exchange ◽  
Raft Polymerization ◽  
Animal Experiments ◽  
Chemical Exchange Saturation Transfer ◽  
Saturation Transfer ◽  
Cest Imaging

Abstract Background Nanomedicine is a promising new approach to cancer treatment that avoids the disadvantages of traditional chemotherapy and improves therapeutic indices. However, the lack of a real-time visualization imaging technology to monitor drug distribution greatly limits its clinical application. Image-tracked drug delivery is of great clinical interest; it is useful for identifying those patients for whom the therapy is more likely to be beneficial. This paper discusses a novel nanomedicine that displays features of nanoparticles and facilitates functional magnetic resonance imaging but is challenging to prepare. Results To achieve this goal, we synthesized an acylamino-containing amphiphilic block copolymer (polyethylene glycol-polyacrylamide-polyacetonitrile, PEG-b-P(AM-co-AN)) by reversible addition-fragmentation chain transfer (RAFT) polymerization. The PEG-b-P(AM-co-AN) has chemical exchange saturation transfer (CEST) effects, which enable the use of CEST imaging for monitoring nanocarrier accumulation and providing molecular information of pathological tissues. Based on PEG-b-P(AM-co-AN), a new nanomedicine PEG-PAM-PAN@DOX was constructed by nano-precipitation. The self-assembling nature of PEG-PAM-PAN@DOX made the synthesis effective, straightforward, and biocompatible. In vitro studies demonstrate decreased cytotoxicity of PEG-PAM-PAN@DOX compared to free doxorubicin (half-maximal inhibitory concentration (IC50), mean ~ 0.62 μg/mL vs. ~ 5 μg/mL), and the nanomedicine more efficiently entered the cytoplasm and nucleus of cancer cells to kill them. Further, in vivo animal experiments showed that the nanomedicine developed was not only effective against breast cancer, but also displayed an excellent sensitive CEST effect for monitoring drug accumulation (at about 0.5 ppm) in tumor areas. The CEST signal of post-injection 2 h was significantly higher than that of pre-injection (2.17 ± 0.88% vs. 0. 09 ± 0.75%, p < 0.01). Conclusions The nanomedicine with CEST imaging reflects the characterization of tumors and therapeutic functions has great potential medical applications.

scholarly journals Method for high-resolution imaging of creatine in vivo using chemical exchange saturation transfer

2013 ◽  
Vol 71 (1) ◽  
pp. 164-172 ◽  
Author(s):  
Feliks Kogan ◽  
Mohammad Haris ◽  
Anup Singh ◽  
Kejia Cai ◽  
Catherine Debrosse ◽  
...  
Keyword(s):  
High Resolution ◽  
Chemical Exchange ◽  
Chemical Exchange Saturation Transfer ◽  
High Resolution Imaging ◽  
Saturation Transfer ◽  
Resolution Imaging

Dysprosium(III) and thulium(III) complexes of DO3A-monoanilides: an investigation of electronic effects on their relaxometric and amide-based PARACEST properties

2015 ◽  
Vol 93 (2) ◽  
pp. 244-252 ◽  
Author(s):  
Melissa M. Lewis ◽  
Mark Milne ◽  
Robert Bartha ◽  
Robert H.E. Hudson
Keyword(s):  
Magnetic Properties ◽  
Chemical Exchange ◽  
Chemical Exchange Saturation Transfer ◽  
Amide Proton ◽  
Saturation Transfer ◽  
Ph Sensors ◽  
Electronic Effects ◽  
Alkaline Conditions ◽  
Electron Donating Groups ◽  
Potential Use

A series of 1,4,7,10-tetraazacyclododecane-1,4,7-triyl)triacetate monoamide (DO3A-monoanilide) complexes Dy3+ and Tm3+ were prepared and their magnetic properties evaluated in the context of their potential use as pH sensors. The ligands varied by para-substitution of the aniline moiety and represent electron-withdrawing and electron-donating groups. Only the Tm3+ complexes produced chemical exchange saturation transfer (CEST) spectra with CEST intensities due to the amide proton ranging from 1% to 8%. A maximum CEST signal was observed under slightly alkaline conditions (pH ∼8) when electron-donating groups were present, whereas the strongly electron-withdrawing nitro group produced a maximum CEST at neutral pH (pH = 7). The T1 and T2 relaxivities of the Dy3+ and Tm3+ complexes were also assessed. The T1 relaxivities of the Dy3+ and Tm3+ complexes were both low (r1 ≤ 0.3 mM−1 s−1, 25 °C, pH = 7) but, as expected, the Dy3+ complexes had much higher T2 relaxivities (r2 = 2–7 mM−1 s−1, 25 °C, pH = 7) as compared to the Tm3+-based chelates (r2 ≤ 0.09 mM−1 s−1, 25 °C, pH = 7).

scholarly journals Quantifying amide proton exchange rate and concentration in chemical exchange saturation transfer imaging of the human brain

NeuroImage ◽  
2019 ◽  
Vol 189 ◽  
pp. 202-213 ◽  
Author(s):  
Hye-Young Heo ◽  
Zheng Han ◽  
Shanshan Jiang ◽  
Michael Schär ◽  
Peter C.M. van Zijl ◽  
...  
Keyword(s):  
Exchange Rate ◽  
Human Brain ◽  
Chemical Exchange ◽  
Proton Exchange ◽  
Chemical Exchange Saturation Transfer ◽  
Amide Proton ◽  
Saturation Transfer ◽  
Amide Proton Exchange
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