Neurite orientation dispersion and density imaging for evaluating the severity of neonatal hypoxic-ischemic encephalopathy in rats
Neurite orientation dispersion and density imaging for evaluating the severity of neonatal hypoxic-ischemic encephalopathy in rats
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DOI：
10.1016/j.mri.2019.07.013
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发表时间：
2019-10-01
影响因子：
2.5
通讯作者：
Fukuchi, Kazuki
中科院分区：
文献类型：
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作者：
Ohki, Akiko;Saito, Shigeyoshi;Fukuchi, Kazuki
目的：评价神经突定向弥散和密度成像（NODDI）在7.0 T磁共振成像纵向评估新生儿缺氧缺血性脑病（HI）严重程度中的应用价值。方法：13只8日龄Wistar大鼠进行左颈总动脉单侧结扎，然后进行轻度（1小时，n = 6）或重度（2小时，n = 7）缺氧暴露（8% 02,34℃）。在HI损伤后1、24、72和168 h，用水平7.0 T扫描仪获得扩散加权、T-2加权（T2W）和流动敏感交替反演恢复图像。计算各组（轻度和重度）在各时间点（1、24、72、168 h）的各向异性分数（FA）、表观扩散系数（ADC）、细胞内体积分数（ICVF）、各向同性体积分数（ISO）、取向弥散指数（ODI）和脑血流量（CBF）值。ICVF、ISO、ODI为NODDI参数。结果：两组1h后T2W图像均可见左半球脑损伤为轻度高信号。仅在重度组，信号高强度在168 h内呈时间依赖性增加。ADC和CBF在任何区域内各组之间均无显著差异。在1至168 h（皮质、纹状体或白质）的不同时间点，重度组的ICVF和ODI明显高于轻度组，而轻度组的FA在168 h（皮质和白质）明显高于重度组。重度组在72 h（纹状体）和168 h（所有地区）的ISO高于轻度组，而轻度组在24 h（所有地区）的ISO明显高于重度组。结论：在这里，ODI，一个NODDI指标，确定了轻度和重度HI损伤之间的早期差异。我们的研究结果支持NODDI在确定大鼠新生儿HI脑病严重程度方面的潜在效用。
Purpose: To evaluate the utility of neurite orientation dispersion and density imaging (NODDI) for longitudinally assessing neonatal hypoxic-ischemic (HI) encephalopathy severity with 7.0 T magnetic resonance imaging.Methods: Thirteen 8-day-old Wistar rats underwent unilateral ligation of the left common carotid artery followed by mild (1 h; n = 6) or severe (2 h; n = 7) hypoxic exposure (8% 02, 34 degrees C). Diffusion-weighted, T-2-weighted (T2W), and flow-sensitive alternating inversion recovery images were obtained with a horizontal 7.0 T scanner at 1, 24, 72, and 168 h after HI insult. The fractional anisotropy (FA), apparent diffusion coefficient (ADC), intracellular volume fraction (ICVF), isotropic volume fraction (ISO), orientation dispersion index (ODI), and cerebral blood flow (CBF) values were calculated for each group (mild and severe) at each time point (1, 24, 72, and 168 h). ICVF, ISO, and ODI were the NODDI parameters.Results: Left hemisphere brain damage was identified as slight hyperintensity on T2W images after 1 h in both groups. In the severe group only, the signal hyperintensity increased time-dependently over 168 h. The ADC and CBF were not significantly different between the groups within any region. The ICVF and ODI were significantly higher in the severe vs. mild group at various points between 1 and 168 h (cortex, striatum, or white matter), whereas the FA was significantly higher in the mild vs. severe group at 168 h (cortex and white matter). The ISO was higher in the severe vs. mild group at 72 h (striatum) and 168 h (all regions), while the ISO was significantly higher in the mild vs. severe group at 24 h (all regions).Conclusion: Here, ODI, a NODDI metric, identified early differences between mild and severe HI injuries. Our findings support the potential utility of NODDI for determining neonatal HI encephalopathy severity in rats.