From the Centre Hospitalier Universitaire (CHU) de Bordeaux, Department of Radiology and Diagnostic Neuroimaging, Bordeaux, France (P.A.L., F.M., V.D., T.T.); University of Bordeaux, Bordeaux, France (P.A.L., F.M., G.O., S.S., V.D., I.S., T.T.); CHU de Lille, Department of Neuroradiology, Lille, France (G.K., R.L.); University of Lille, Lille, France (G.K., R.L.); CHU de Bordeaux, Public Health Center, Methodological Support Unit for Clinical and Epidemiological Research, Bordeaux, France (R.G., J.A., P.P.); CHU de Bordeaux, Neurovascular Unit, Bordeaux, France (S.S., P.R., I.S.); and Institut National de la Santé et de la Recherche Médicale, Neurocentre Magendie, Bordeaux, France (V.D., T.T.).
Radiology. 2019 May;291(2):438-448. doi: 10.1148/radiol.2019182126. Epub 2019 Mar 12.
Background The substantia nigra (SN) is suspected to be affected after remote infarction, in view of its large array of connections with the supratentorial brain. Whether secondary involvement of SN worsens overall clinical outcome after a supratentorial stroke has not previously been studied. Purpose To assess longitudinal changes in SN R2* by using MRI in the setting of ipsilesional supratentorial infarct and the relationship of SN signal change to clinical outcome. Materials and Methods Participants prospectively included from 2012 to 2015 were evaluated at 24-72 hours (baseline visit) and at 1 year with MRI to quantify R2*. The SN was segmented bilaterally to calculate an R2* asymmetry index (SN-AI); greater SN-AI indicated greater relative R2* in the ipsilateral compared with contralateral SN. The 95th percentile of R2* (hereafter, SN-AI) was compared according to infarct location with mixed linear regression models. We also conducted voxel-based comparisons of R2* and identified individual infarcted voxels associated with high SN-AI through voxel-based lesion-symptom mapping. Multivariable regression models tested the association between SN-AI and clinical scores. Results A total of 181 participants were evaluated (127 men, 54 women; mean age ± standard deviation, 64.2 years ± 13.1; 75 striatum infarcts, 106 other locations). Visual inspection, SN-AI, and average maps consistently showed higher SN R2* at 1 year if ipsilateral striatum was infarcted than if it was not (SN-AI, 4.25 vs -0.88; < .001), but this was not observed at baseline. The striatal location of the infarct was associated with higher SN-AI at 1 year independently from infarct volume, SN-AI at baseline, microbleeds, age, and sex (β = 4.99; < .001). Voxel-based lesion-symptom mapping confirmed that striatum but also insula, internal capsule, and external capsule were associated with higher SN-AI at 1 year. SN-AI was an independent contributor of poor motor outcome (Box and Block Test, β = -.62 points; = .01). Conclusion In patients with stroke, greater substantia nigra R2*, likely reflective of greater iron content, can be observed at 1 year ipsilateral from remote infarcts of specific location, which is associated with worse motor function. © RSNA, 2019 See also the editorial by Vernooij in this issue.
背景 鉴于黑质（SN）与大脑上区有大量的连接，因此怀疑其在远处梗塞后受到影响。以前尚未研究过 SN 的继发性受累是否会使大脑上区卒中后的整体临床结局恶化。目的 在同侧大脑上区梗死的情况下，通过 MRI 评估 SN R2的纵向变化，以及 SN 信号变化与临床结局的关系。材料与方法 2012 年至 2015 年前瞻性纳入参与者，在 24-72 小时（基线就诊）和 1 年时进行 MRI 评估以量化 R2。双侧分割 SN 以计算 R2不对称指数（SN-AI）；SN-AI 越大，表明同侧 SN 的 R2相对较高。采用混合线性回归模型比较根据梗死位置的第 95 个百分位数（以下简称 SN-AI）。我们还对 R2进行了基于体素的比较，并通过基于体素的病变-症状映射确定了与高 SN-AI 相关的个体梗死体素。多变量回归模型测试了 SN-AI 与临床评分之间的关联。结果 共评估了 181 名参与者（127 名男性，54 名女性；平均年龄±标准差，64.2 岁±13.1 岁；75 例纹状体梗死，106 例其他部位梗死）。如果同侧纹状体发生梗死，视觉检查、SN-AI 和平均图均一致显示 1 年后 SN 的 R2更高（SN-AI，4.25 比-0.88；<0.001），但基线时未见此现象。梗死的纹状体位置与 1 年后 SN-AI 升高独立相关，与梗死体积、基线时的 SN-AI、微出血、年龄和性别无关（β=4.99；<0.001）。基于体素的病变-症状映射证实，纹状体以及脑岛、内囊和外囊也与 1 年后 SN-AI 升高有关。SN-AI 是运动功能不良的独立预测因素（Box 和 Block 测试，β=-.62 分；=0.01）。结论 在发生卒中的患者中，在大脑上区对侧的特定部位出现的黑质 R2*升高（可能反映了铁含量的增加），可在 1 年后观察到，与运动功能更差相关。
