Background and Purpose—Widespread reductions in white matter integrity are associated with cognitive dysfunction in sickle cell anemia. Silent cerebral infarction (SCI), vasculopathy (VSC), and low hemoglobin concentration (Hb) are implicated; we aimed to determine independent contributions to microstructural white matter injury and whether white matter integrity differs across arterial territories.Methods—Sixty two children with sickle cell anemia aged 6 to 19 years were prospectively studied at Muhimbili National Hospital, Tanzania. SCI± and VSC± were identified on magnetic resonance imaging (MRI)/magnetic resonance angiography (MRA) scans by 2 neuroradiologists. Tract-based spatial statistics tested for voxel-wise differences in diffusion tensor imaging metrics (ie, fractional anisotropy, mean diffusivity, radial diffusivity, and axial diffusivity) between SCI± and VSC± groups, with correlations between diffusion tensor imaging metrics and Hb. In tract-based spatial statistics analyses, potentially mediating factors (ie, age, sex, as well as Hb, SCI, and/or vasculopathy) were covariates. Differences in mean diffusion tensor imaging metrics across regions of interest in arterial territories were explored.Results—Compared with SCI− patients (n=45), SCI+ patients (n=17) exhibited increased radial diffusivity in multiple regions; negative relationships were observed between mean diffusivity, axial diffusivity, and Hb (P<0.005). Compared with VSC− patients (n=49), mild (n=6) or moderate (n=7) VSC+ patients exhibited reduced fractional anisotropy in widespread regions (P<0.05) including the anterior longitudinal fasciculi, corpus callosum, internal capsule, corona radiata, and corticospinal tracts. Overall, the posterior cerebral arterial territory had higher mean mean diffusivity and mean radial diffusivity than the anterior and middle cerebral arterial territories, although no patient had vasculopathy in this area. There was an interaction between territory and vasculopathy.Conclusions—SCI, vasculopathy, and Hb are independent risk factors, and thus treatment targets, for diffuse white matter injury in patients with sickle cell anemia. Exacerbation of hemodynamic stress may play a role.

中文翻译：

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坦桑尼亚镰状细胞性贫血儿童的白质完整性：扩散张量成像研究。

背景和目的——白质完整性的广泛降低与镰状细胞性贫血的认知功能障碍有关。涉及静默性脑梗塞 (SCI)、血管病变 (VSC) 和低血红蛋白浓度 (Hb)；我们旨在确定对微结构白质损伤的独立贡献，以及白质完整性是否在不同的动脉区域存在差异。方法——在坦桑尼亚 Muhimbili 国立医院对 62 名 6 至 19 岁的镰状细胞性贫血儿童进行了前瞻性研究。SCI± 和 VSC± 由 2 名神经放射科医师在磁共振成像 (MRI)/磁共振血管造影 (MRA) 扫描中发现。基于区域的空间统计测试了扩散张量成像指标的体素差异（即分数各向异性、平均扩散率、径向扩散率、SCI±和VSC±组之间的轴向扩散率），扩散张量成像指标和Hb之间的相关性。在基于束的空间统计分析中，潜在的中介因素（即年龄、性别以及 Hb、SCI 和/或血管病变）是协变量。探讨了动脉区域中感兴趣区域的平均扩散张量成像指标的差异。结果——与 SCI- 患者 (n=45) 相比，SCI+ 患者 (n=17) 在多个区域表现出增加的径向扩散率；在平均扩散率、轴向扩散率和 Hb 之间观察到负相关关系（探讨了动脉区域中感兴趣区域的平均扩散张量成像指标的差异。结果——与 SCI- 患者 (n=45) 相比，SCI+ 患者 (n=17) 在多个区域表现出增加的径向扩散率；在平均扩散率、轴向扩散率和 Hb 之间观察到负相关关系（探讨了动脉区域中感兴趣区域的平均扩散张量成像指标的差异。结果——与 SCI- 患者 (n=45) 相比，SCI+ 患者 (n=17) 在多个区域表现出增加的径向扩散率；在平均扩散率、轴向扩散率和 Hb 之间观察到负相关关系（P <0.005）。与 VSC− 患者 (n=49) 相比，轻度 (n=6) 或中度 (n=7) VSC+ 患者在包括前纵束、胼胝体、内囊、放射冠和皮质脊髓束。总体而言，大脑后动脉区域的平均扩散率和平均径向扩散率高于大脑前动脉和大脑中动脉区域，尽管该区域没有患者出现血管病变。区域和血管病变之间存在相互作用。结论——SCI、血管病变和 Hb 是镰状细胞性贫血患者弥漫性白质损伤的独立危险因素，因此是治疗目标。血流动力学压力的加重可能起作用。