在一项新生仔猪脑病的初步研究中，纹状体的平均扩散率与急性神经元死亡相关，但与较轻的神经元损伤无关。
Mean Diffusivity in Striatum Correlates With Acute Neuronal Death but Not Lesser Neuronal Injury in a Pilot Study of Neonatal Piglets With Encephalopathy.
作者信息
Lee Jennifer K, Liu Dapeng, Raven Erika P, Jiang Dengrong, Liu Peiying, Qin Qin, Kulikowicz Ewa, Santos Polan T, Adams Shawn, Zhang Jiangyang, Koehler Raymond C, Martin Lee J, Tekes Aylin
机构信息
Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University (JHU), Baltimore, Maryland, USA.
Department of Radiology, Johns Hopkins University, Baltimore, Maryland, USA.
出版信息
J Magn Reson Imaging. 2020 Oct;52(4):1216-1226. doi: 10.1002/jmri.27181. Epub 2020 May 12.
BACKGROUND
Diffusion MRI is routinely used to evaluate brain injury in neonatal encephalopathy. Although abnormal mean diffusivity (MD) is often attributed to cytotoxic edema, the specific contribution from neuronal pathology is unclear.
PURPOSE
To determine whether MD from high-resolution diffusion tensor imaging (DTI) can detect variable degrees of neuronal degeneration and pathology in piglets with brain injury induced by excitotoxicity or global hypoxia-ischemia (HI) with or without overt infarction.
STUDY TYPE
Prospective.
ANIMAL MODEL
Excitotoxic brain injury was induced in six neonatal piglets by intrastriatal stereotaxic injection of the glutamate receptor agonist quinolinic acid (QA). Three piglets underwent global HI or a sham procedure. Piglets recovered for 20-96 hours before undergoing MRI (n = 9).
FIELD STRENGTH/SEQUENCE: 3.0T MRI with DTI, T - and T -weighted imaging.
ASSESSMENT
MD, fractional anisotropy (FA), and qualitative T injury were assessed in the putamen and caudate. The cell bodies of normal neurons, degenerating neurons (excitotoxic necrosis, ischemic necrosis, or necrosis-apoptosis cell death continuum), and injured neurons with equivocal degeneration were counted by histopathology.
STATISTICAL TESTS
Spearman correlations were used to compare MD and FA to normal, degenerating, and injured neurons. T injury and neuron counts were evaluated by descriptive analysis.
RESULTS
The QA insult generated titratable levels of neuronal pathology. In QA, HI, and sham piglets, lower MD correlated with higher ratios of degenerating-to-total neurons (P < 0.05), lower ratios of normal-to-total neurons (P < 0.05), and greater numbers of degenerating neurons (P < 0.05). MD did not correlate with abnormal neurons exhibiting nascent injury (P > 0.99). Neuron counts were not related to FA (P > 0.30) or to qualitative injury from T -weighted MRI.
DATA CONCLUSION
MD is more accurate than FA for detecting neuronal degeneration and loss during acute recovery from neonatal excitotoxic and HI brain injury. MD does not reliably detect nonfulminant, nascent, and potentially reversible neuronal injury.
EVIDENCE LEVEL
1 TECHNICAL EFFICACY: Stage 2 J. Magn. Reson. Imaging 2020;52:1216-1226.
背景
扩散加权磁共振成像（Diffusion MRI）常用于评估新生儿脑病中的脑损伤。尽管平均扩散率（MD）异常常被归因于细胞毒性水肿，但神经元病理学的具体作用尚不清楚。
目的
确定高分辨率扩散张量成像（DTI）中的MD是否能检测出由兴奋性毒性或全脑缺氧缺血（HI）诱导的脑损伤仔猪中不同程度的神经元变性和病理学改变，无论有无明显梗死。
研究类型
前瞻性研究。
动物模型
通过纹状体内立体定向注射谷氨酸受体激动剂喹啉酸（QA），在6只新生仔猪中诱导兴奋性毒性脑损伤。3只仔猪接受全脑HI或假手术。仔猪恢复20 - 96小时后进行MRI检查（n = 9）。
场强/序列：3.0T MRI，采用DTI、T1和T2加权成像。
评估
在壳核和尾状核中评估MD、分数各向异性（FA）和T2加权成像的定性损伤。通过组织病理学对正常神经元、变性神经元（兴奋性毒性坏死、缺血性坏死或坏死 - 凋亡细胞死亡连续体）以及具有可疑变性的损伤神经元的细胞体进行计数。
统计检验
采用Spearman相关性分析比较MD和FA与正常、变性和损伤神经元的关系。通过描述性分析评估T2加权成像损伤和神经元计数。
结果
QA损伤产生了可滴定水平的神经元病理学改变。在QA、HI和假手术仔猪中，较低的MD与变性神经元与总神经元的较高比例相关（P < 0.05），正常神经元与总神经元的较低比例相关（P < 0.05），以及更多的变性神经元数量相关（P < 0.05）。MD与表现为新生损伤的异常神经元无相关性（P > 0.99）。神经元计数与FA无关（P > 0.30），也与T2加权MRI的定性损伤无关。
数据结论
在新生儿兴奋性毒性和HI脑损伤急性恢复期间，MD在检测神经元变性和丢失方面比FA更准确。MD不能可靠地检测非暴发性、新生的和潜在可逆的神经元损伤。
证据水平
1 技术效能：2级 《磁共振成像杂志》2020年；52:1216 - 1226。
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