Comparison of Chemical Exchange Saturation Transfer Imaging with Diffusion-weighted Imaging and Magnetic Resonance Spectroscopy in a Rat Model of Hypoxic-ischemic Encephalopathy

Abstract

This study aimed to evaluate the effect of chemical exchange saturation transfer (CEST) on the ischemic regions in hypoxic-ischemic encephalopathy (HIE) in comparison with diffusion-weighted imaging (DWI) and magnetic resonance spectroscopy (MRS) using a 7T-MRI. Methods: We used neonatal rats (n = 8), aged 8 days, to clarify the progression of HIE. The rat model of HIE was developed by ligating and severing the left common carotid artery, followed by 45 minutes of recovery, and 60 minutes of hypoxia (8% O 2 /92% N 2 ; 34°C). At 0-2 and 24 hours after the onset of HIE, CEST imaging, DWI, and MRS were performed with a 7T-MRI. The magnetization transfer ratio (MTR) asymmetry curves and four MTR asymmetry maps at 0.5, 1.0, 2.0, and 3.5 ppm were calculated using the CEST images. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) maps were calculated by DWI, and brain metabolites were assessed by MRS. Results: In the ischemic regions of neonatal rats, FA was significantly increased at 0-2 hours and decreased at 24 hours after the onset of HIE. ADC in the ipsilateral side was significantly lower than that of contralateral side. All rats with HIE showed hypointense areas on MTR asymmetry maps (2.0 and 3.5 ppm), that did not correspond with the hyperintense areas on DWI. In addition, a significant increase in lactate levels was observed at 0-2 and 24 hours after the onset of HIE. Conclusion: CEST MTR maps did not correspond with the hyperintense areas on DWI at 0-2 and 24 hours after the onset of HIE. The change of multi offset CEST signal may be primarily related to the brain metabolites and pH alterations, such as that caused by lactate, after the onset of HIE.

Magnetic resonance imaging of umbilical cord stem cells labeled with superparamagnetic iron oxide nanoparticles: effects of labelling and transplantation parameters

“…Second, the therapeutic efficacy of the labeled UC-MSCs was not investigated. As the UC-MSCs can be used safely and with minimal ethical complications, they are expected to become the preferred therapeutic stem cell type, especially in neonatal disorders, such as hypoxic-ischemic encephalopathy 46 – 48 . Further studies are necessary to investigate the possibilities of using UC-MSCs in cell-based treatments.…”

Visualization of Spatial Distribution of Spermatogenesis in Mouse Testes Using Creatine Chemical Exchange Saturation Transfer Imaging

“…Chemical exchange saturation transfer (CEST) imaging can evaluate metabolites with exchangeable protons such as amide and amine protons by using prolonged, selective saturation pulses 10–15 . CEST imaging that specifically targets Cr amine protons is known as CrCEST imaging, and it has been applied in human muscle and brain 14,16–21 .…”

Accurate Estimation of the Duration of Testicular Ischemia Using Creatine Chemical Exchange Saturation Transfer (CrCEST) Imaging

“…Like 1 H MRS, chemical exchange saturation transfer (CEST) imaging is a magnetic resonance imaging (MRI) technique for evaluating low‐concentration metabolites, but it overcomes some of the limitations of 1 H MRS 12–15 . Using prolonged and selective saturation pulses, CEST imaging can evaluate metabolites with exchangeable protons such as amide and amine protons.…”