Long-term Brain Tissue Monitoring after Semi-brain Irradiation in Rats Using Proton Magnetic Resonance Spectroscopy

Abstract

Background:In head and neck neoplasm survivors treated with brain irradiation, metabolic alterations would occur in the radiation-induced injury area. The mechanism of these metabolic alterations has not been fully understood, while the alternations could be sensitively detected by proton (1H) nuclear magnetic resonance spectroscopy (MRS). In this study, we investigated the metabolic characteristics of radiation-induced brain injury through a long-term follow-up after radiation treatment using MRS in vivo.Methods:A total of 12 adult Sprague-Dawley rats received a single dose of 30 Gy radiation treatment to semi-brain (field size: 1.0 cm × 2.0 cm; anterior limit: binocular posterior inner canthus connection; posterior limit: external acoustic meatus connection; internal limit: sagittal suture). Conventional magnetic resonance imaging and single-voxel 1H-MRS were performed at different time points (in month 0 before irradiation as well as in the 1st, 3rd, 5th, 7th, and 9th months after irradiation) to investigate the alternations in irradiation field. N-acetylaspartate/choline (NAA/Cho), NAA/creatinine (Cr), and Cho/Cr ratios were measured in the bilateral hippocampus and quantitatively analyzed with a repeated-measures mixed-effects model and multiple comparison test.Results:Significant changes in the ratios of NAA/Cho (F = 57.37, Pg < 0.001), NAA/Cr (F = 54.49, Pg < 0.001), and Cho/Cr (F = 9.78, Pg = 0.005) between the hippocampus region of the irradiated semi-brain and the contralateral semi-brain were observed. There were significant differences in NAA/Cho (F = 9.17, Pt < 0.001) and NAA/Cr (F = 13.04, Pt < 0.001) ratios over time. The tendency of NAA/Cr to change with time showed no significant difference between the irradiated and contralateral sides. Nevertheless, there were significant differences in the Cho/Cr ratio between these two sides.Conclusions:MRS can sensitively detect metabolic alternations. Significant changes of metabolites ratio in the first few months after radiation treatment reflect the metabolic disturbance in the acute and early-delayed stages of radiation-induced brain injuries.

Neuroprotective effect of resveratrol against radiation after surgically induced brain injury by reducing oxidative stress, inflammation, and apoptosis through NRf2/HO‐1/NF‐κB signaling pathway

“…A spectrophotometer was used to read the absorbance of each well at 450 nm, and the contents of each well were calculated by using a standard curve. [14] 2.4 | Quantitative measurement of blood proinflammatory cytokines…”

Hippocampal changes in inflammasomes, apoptosis, and MEMRI after radiation-induced brain injury in juvenile rats

“…MRS can be used to monitor brain tumor progression and is helpful for identifying radiation necrosis after radiation therapy [22,23]. In studies of radiation brain damage, MRS has been shown to detect early metabolic changes in normal irradiated brain tissue [24][25][26].…”

Early metabolic characterization of brain tissues after whole body radiation based on gas chromatography–mass spectrometry in a rat model

“…Therefore, investigating the early metabolic characterization of brain tissues following irradiation may present clues to the mechanism of radiation‐induced brain injury and modify the therapeutic strategy. In recent years, magnetic resonance spectroscopy (MRS) has been used to measure the metabolic changes in radiation‐induced brain injury, and has suggested that choline/creatine and N ‐acetylaspartate/creatine are significantly decreased in clinical patients and rats following irradiation (Chen, Cheng, & Zhou, ; Bálentová et al, ; Sundgren et al, ). However, the earliest time point of monitoring these changes based on MRS was at week 3 of radiation exposure (Sundgren et al, ).…”