Evaluation of Brain Impairment Using Proton Exchange Rate MRI in a Kainic Acid-Induced Rat Model of Epilepsy.

IF 3 4区医学 Q2 RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING Molecular Imaging and Biology Pub Date : 2025-02-01 Epub Date: 2025-01-02 DOI:10.1007/s11307-024-01980-4

Huanhuan Yang, Qiting Wu, Lin Li, Yin Wu

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Abstract

Purpose: Proton exchange rate (K_ex) is a valuable biophysical metric. K_ex MRI may augment conventional structural MRI by revealing brain impairments at the molecular level. This study aimed to investigate the feasibility of K_ex MRI in evaluating brain injuries at multiple epilepsy stages.

Procedures: Six adult rats with epilepsy induced by intra-amygdalae administration of kainic acid (KA) underwent MRI experiment at 11.7 T. Two MRI scans, including T₁ mapping and CEST imaging under three B₁ amplitudes of 0.75, 1.0, and 1.5 μT, were conducted before and 2, 7, and 28 days after KA injection. Quasi-steady-state analysis was performed to reconstruct equilibrium Z spectra. Direct saturation was resolved using a multi-pool Lorentzian model and removed from Z spectra. The residual spectral signal (ΔZ) was used to construct the omega plot of (1-ΔZ)/ΔZ as a linear function of 1/ $ω_{1}^{2}$ , from which K_ex was quantified from the X-axis intercept. One-way ANOVA or two-tailed paired student's t-test was employed with P < 0.05 as statistically significant.

Results: All animals exhibited repetitive status epilepticus with IV to V seizure stages after KA injection. At day 28, K_ex values in the hippocampus and cerebral cortex at the surgical hemisphere with KA injection were significantly higher than that at the time points of control and/or day 2 in the same regions (P < 0.01). Moreover, the values were significantly higher than that in respective contralateral regions at day 28 (P < 0.02). No substantial changes of K_ex were seen in bilateral thalamus or contralateral hemisphere among time points (all P > 0.05).

Conclusions: K_ex increase significantly in the cerebral cortex and hippocampus at the surgical hemisphere, especially at day 28, likely due to substantial alterations at chronic epilepsy stage. K_ex MRI is promising to evaluate brain impairment, facilitating the diagnosis and evaluation of neurological disorders.

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质子交换率MRI评价凯尼克酸致癫痫大鼠模型脑损伤。

目的：质子交换率（Kex）是一种有价值的生物物理指标。Kex MRI可以通过在分子水平上显示脑损伤来增强传统的结构MRI。本研究旨在探讨Kex MRI评估多期癫痫脑损伤的可行性。方法：6只杏仁核内给药kainic acid （KA）致癫痫的成年大鼠，于11.7 t时进行MRI实验，分别于KA注射前、注射后2、7、28天分别在0.75、1.0、1.5 μT 3个B1振幅下进行T1作图和CEST成像。准稳态分析重建平衡态Z谱。直接饱和度用多池洛伦兹模型解决，并从Z谱中去除。利用残差光谱信号（ΔZ）构建（1-ΔZ）/ΔZ作为1/ ω 1 2的线性函数的ω图，从中从x轴截距量化Kex。采用单因素方差分析或双尾配对学生t检验，P值为P。结果：所有动物在注射KA后均表现出重复的癫痫持续状态，发作期为IV至V。第28天，KA注射后手术半球海马和大脑皮层的Kex值显著高于对照组和/或第2天的同一区域（各时间点间双侧丘脑和对侧半球均有P < 0.05）。结论：手术半球大脑皮层和海马中Kex显著增加，特别是在第28天，可能是由于慢性癫痫期的实质性改变。Kex MRI有望评估脑损伤，促进神经系统疾病的诊断和评估。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Molecular Imaging and Biology 医学-核医学

CiteScore

6.90

自引率

3.20%

发文量

审稿时长

3 months

期刊介绍： Molecular Imaging and Biology (MIB) invites original contributions (research articles, review articles, commentaries, etc.) on the utilization of molecular imaging (i.e., nuclear imaging, optical imaging, autoradiography and pathology, MRI, MPI, ultrasound imaging, radiomics/genomics etc.) to investigate questions related to biology and health. The objective of MIB is to provide a forum to the discovery of molecular mechanisms of disease through the use of imaging techniques. We aim to investigate the biological nature of disease in patients and establish new molecular imaging diagnostic and therapy procedures. Some areas that are covered are: Preclinical and clinical imaging of macromolecular targets (e.g., genes, receptors, enzymes) involved in significant biological processes. The design, characterization, and study of new molecular imaging probes and contrast agents for the functional interrogation of macromolecular targets. Development and evaluation of imaging systems including instrumentation, image reconstruction algorithms, image analysis, and display. Development of molecular assay approaches leading to quantification of the biological information obtained in molecular imaging. Study of in vivo animal models of disease for the development of new molecular diagnostics and therapeutics. Extension of in vitro and in vivo discoveries using disease models, into well designed clinical research investigations. Clinical molecular imaging involving clinical investigations, clinical trials and medical management or cost-effectiveness studies.