From the Department of Radiology and Imaging, Muhimbili University of Health and Allied Sciences, Dar Es Salaam, Tanzania (M.J., R.K.).
Muhimbili Sickle Cell Program (M.J., R.Z.S., J.M.), Muhimbili University of Health and Allied Sciences.
Stroke. 2020 Apr;51(4):1166-1173. doi: 10.1161/STROKEAHA.119.027097. Epub 2020 Mar 6.
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 (<0.005). Compared with VSC- patients (n=49), mild (n=6) or moderate (n=7) VSC+ patients exhibited reduced fractional anisotropy in widespread regions (<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.
背景与目的- 在镰状细胞贫血患者中，广泛的白质完整性降低与认知功能障碍有关。沉默性脑梗死（SCI）、血管病变（VSC）和低血红蛋白浓度（Hb）与此有关；我们旨在确定它们对微观白质损伤的独立贡献，以及白质完整性是否因动脉区域而异。方法- 坦桑尼亚穆希比利国家医院前瞻性研究了 62 名年龄在 6 至 19 岁的镰状细胞贫血儿童。2 位神经放射科医生通过磁共振成像（MRI）/磁共振血管造影（MRA）扫描识别 SCI±和 VSC±。基于体素的空间统计学测试了弥散张量成像指标（即各向异性分数、平均弥散系数、径向弥散系数和轴向弥散系数）在 SCI±和 VSC±组之间的体素差异，弥散张量成像指标与 Hb 之间存在相关性。在基于体素的空间统计学分析中，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。还探索了动脉区域内感兴趣区域的平均弥散张量成像指标差异。结果- 与 SCI- 患者（n=45）相比，SCI+ 患者（n=17）在多个区域表现出更高的径向弥散系数；平均弥散系数、轴向弥散系数与 Hb 呈负相关（<0.005）。与 VSC- 患者（n=49）相比，轻度（n=6）或中度（n=7）VSC+ 患者在广泛区域（包括前纵束、胼胝体、内囊、辐射冠和皮质脊髓束）表现出较低的各向异性分数（<0.05）。总体而言，后大脑动脉区域的平均弥散系数和平均径向弥散系数高于前大脑和中大脑动脉区域，尽管该区域没有患者存在血管病变。区域和血管病变之间存在交互作用。结论- SCI、血管病变和 Hb 是镰状细胞贫血患者弥漫性白质损伤的独立危险因素，也是治疗靶点。血流动力学应激的加剧可能起作用。
