Vascular Abnormalities within Normal Appearing Tissue in Chronic Traumatic Brain Injury
Vascular Abnormalities within Normal Appearing Tissue in Chronic Traumatic Brain Injury
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DOI：
10.1089/neu.2018.5684
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发表时间：
2018-06-07
影响因子：
4.2
通讯作者：
Sandsmark, Danielle
中科院分区：
文献类型：
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作者：
Haber, Margalit;Amyot, Franck;Sandsmark, Danielle
磁共振成像(MRI)是显示创伤性脑损伤(TBI)相关损害的有力工具。外伤性脑软化症通常通过液体衰减反转恢复(FLAIR)序列上的高信号表现来识别。除脑实质损害外，颅脑损伤还常导致脑微血管损伤，但其与脑实质软化的解剖关系尚不清楚。本研究采用多模式磁共振成像技术，对27例慢性脑损伤患者(伤后至少6个月)可见脑软化区和正常脑组织内微结构组织完整性(通过平均弥散率[MD]和各向异性分数[FA])和血管功能改变(通过脑血流量[CBF]和脑血管反应性[CVR])进行评估。15名受试者在MRI上有明显的脑软化，而12名受试者在MRI上没有明显的损害。14名年龄匹配的健康志愿者作为对照。通过动脉自旋标记(ASL)和CVR来评估CBF，方法是测量高碳酸血症期间血氧水平依赖(BOLD)MRI的变化。在FLAIR可见的脑软化区，FA、CBF和CVR显著降低，MD显著增加(P<；所有比较均为0.05)。在外观正常的脑区，只有CVR与对照组相比显著降低(p<；0.05)。这些发现表明，血管功能障碍代表了一种不同于常规MRI发现的结构性损伤的脑损伤内表型，即使在没有可见的结构性损伤的情况下也可能存在，并在创伤后长期存在。CVR可作为创伤性微血管损伤的一种有用的诊断和药效学成像生物标志物。
Magnetic resonance imaging (MRI) is a powerful tool for visualizing traumatic brain injury(TBI)-related lesions. Trauma-induced encephalomalacia is frequently identified by its hyperintense appearance on fluid-attenuated inversion recovery (FLAIR) sequences. In addition to parenchymal lesions, TBI commonly results in cerebral microvascular injury, but its anatomical relationship to parenchymal encephalomalacia is not well characterized. The current study utilized a multi-modal MRI protocol to assess microstructural tissue integrity (by mean diffusivity [MD] and fractional aniosotropy [FA]) and altered vascular function (by cerebral blood flow [CBF] and cerebral vascular reactivity [CVR]) within regions of visible encephalomalacia and normal appearing tissue in 27 chronic TBI (minimum 6 months post-injury) subjects. Fifteen subjects had visible encephalomalacias whereas 12 did not have evident lesions on MRI. Imaging from 14 age-matched healthy volunteers were used as controls. CBF was assessed by arterial spin labeling (ASL) and CVR by measuring the change in blood-oxygen-level-dependent (BOLD) MRI during a hypercapnia challenge. There was a significant reduction in FA, CBF, and CVR with a complementary increase in MD within regions of FLAIR-visible encephalomalacia (p < 0.05 for all comparisons). In normal-appearing brain regions, only CVR was significantly reduced relative to controls (p < 0.05). These findings indicate that vascular dysfunction represents a TBI endophenotype that is distinct from structural injury detected using conventional MRI, may be present even in the absence of visible structural injury, and persists long after trauma. CVR may serve as a useful diagnostic and pharmacodynamic imaging biomarker of traumatic microvascular injury.