Yang Huanhuan, Wu Qiting, Li Lin, Wu Yin
Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China.
Surgery Division, Epilepsy Center, Shenzhen Children's Hospital, Shenzhen, Guangdong, China.
Mol Imaging Biol. 2025 Feb;27(1):1-9. doi: 10.1007/s11307-024-01980-4. Epub 2025 Jan 2.
Proton exchange rate (K) is a valuable biophysical metric. K MRI may augment conventional structural MRI by revealing brain impairments at the molecular level. This study aimed to investigate the feasibility of K MRI in evaluating brain injuries at multiple epilepsy stages.
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 T mapping and CEST imaging under three B 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/ , from which K 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.
All animals exhibited repetitive status epilepticus with IV to V seizure stages after KA injection. At day 28, K 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 were seen in bilateral thalamus or contralateral hemisphere among time points (all P > 0.05).
K 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 MRI is promising to evaluate brain impairment, facilitating the diagnosis and evaluation of neurological disorders.
质子交换率（K）是一种有价值的生物物理指标。K磁共振成像（MRI）可通过在分子水平揭示脑损伤来补充传统的结构MRI。本研究旨在探讨K MRI在评估多个癫痫阶段脑损伤方面的可行性。
6只通过杏仁核内注射 kainic 酸（KA）诱导癫痫的成年大鼠在11.7 T下进行MRI实验。在KA注射前以及注射后2、7和28天进行两次MRI扫描，包括T映射和在0.75、1.0和1.5 μT三个B振幅下的化学交换饱和转移（CEST）成像。进行准稳态分析以重建平衡Z谱。使用多池洛伦兹模型解析直接饱和并从Z谱中去除。剩余光谱信号（ΔZ）用于构建(1 - ΔZ)/ΔZ作为1/ω的线性函数的ω图，从中从X轴截距量化K。采用单因素方差分析或双尾配对学生t检验，P < 0.05为具有统计学意义。
所有动物在KA注射后均表现出IV至V级癫痫发作阶段的反复癫痫持续状态。在第28天，注射KA的手术侧海马和大脑皮质中的K值显著高于同一区域对照时间点和/或第2天的K值（P < 0.01）。此外，在第28天，这些值显著高于各自对侧区域的值（P < 0.02）。在各时间点，双侧丘脑或对侧半球的K值未见实质性变化（所有P > 0.05）。
手术侧大脑皮质和海马中的K值显著增加，尤其是在第28天，这可能是由于慢性癫痫阶段的大量改变所致。K MRI有望用于评估脑损伤，有助于神经系统疾病的诊断和评估。
