Li Rui-Li, Sun Jun, Tang Zhen-Chao, Zhang Jing-Ji, Li Hong-Jun
Department of Radiology, Beijing YouAn Hospital, Capital Medical University, No.8, Xi Tou Tiao, Youanmen Wai, Feng Tai District, Beijing, 100069, China.
School of Mechanical, Electrical & Information Engineering, Shandong University, No.180, West Wenhua Road, Weihai, 264209, Shandong Province, China.
BMC Neurol. 2018 May 10;18(1):66. doi: 10.1186/s12883-018-1069-5.
HIV is a neurotropic virus, and it can bring about neurodegeneration and may even result in cognitive impairments. The precise mechanism of HIV-associated white matter (WM) injury is unknown. The effects of multiple clinical contributors on WM impairments and the relationship between the WM alterations and cognitive performance merit further investigation.
Diffusion tensor imaging (DTI) was performed in 20 antiretroviral-naïve HIV-positive asymptomatic neurocognitive impairment (ANI) adults and 20 healthy volunteers. Whole-brain analysis of DTI metrics between groups was conducted by employing tract-based spatial statistics (TBSS), including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD). DTI parameters were correlated with clinical variables (age, CD4 cell count, CD4/CD8 ratio, plasma viral load and duration of HIV infection) and multiple cognitive tests by using multilinear regression analyses.
DTI quantified diffusion alterations in the corpus callosum and corona radiata (MD increased significantly, P < 0.05) and chronic axonal injury in the corpus callosum, corona radiata, internal capsule, external capsule, posterior thalamic radiation, sagittal stratum, and superior longitudinal fasciculus (AD increased significantly, P < 0.05). The impairments in the corona radiata had significant correlations with the current CD4/CD8 ratios. Increased MD or AD values in multiple white matter structures showed significant associations with many cognitive domain tests.
WM impairments are present in neurologically asymptomatic HIV+ adults, periventricular WM (corpus callosum and corona radiata) are preferential occult injuries, which is associated with axonal chronic damage rather than demyelination. Axonopathy may exist before myelin injury. DTI-TBSS is helpful to explore the WM microstructure abnormalities and provide a new perspective for the investigation of the pathomechanism of HIV-associated WM injury.
人类免疫缺陷病毒（HIV）是一种嗜神经病毒，可导致神经退行性变，甚至可能导致认知障碍。HIV相关白质（WM）损伤的确切机制尚不清楚。多种临床因素对WM损伤的影响以及WM改变与认知表现之间的关系值得进一步研究。
对20名未接受抗逆转录病毒治疗的HIV阳性无症状神经认知障碍（ANI）成人和20名健康志愿者进行扩散张量成像（DTI）。采用基于纤维束的空间统计学（TBSS）对两组之间的DTI指标进行全脑分析，包括分数各向异性（FA）、平均扩散率（MD）、轴向扩散率（AD）和径向扩散率（RD）。通过多线性回归分析，将DTI参数与临床变量（年龄、CD4细胞计数、CD4/CD8比值、血浆病毒载量和HIV感染持续时间）以及多项认知测试相关联。
DTI量化了胼胝体和放射冠的扩散改变（MD显著增加，P < 0.05）以及胼胝体、放射冠、内囊、外囊、丘脑后辐射、矢状层和上纵束的慢性轴突损伤（AD显著增加，P < 0.05）。放射冠的损伤与当前的CD4/CD8比值显著相关。多个白质结构中MD或AD值的增加与许多认知领域测试显示出显著关联。
在神经无症状的HIV+成人中存在WM损伤，脑室周围WM（胼胝体和放射冠）是优先的隐匿性损伤，这与轴突慢性损伤而非脱髓鞘有关。轴突病可能在髓鞘损伤之前就已存在。DTI-TBSS有助于探索WM微观结构异常，并为研究HIV相关WM损伤的发病机制提供新的视角。
