Table_1_Diffusion Tensor Imaging Biomarkers to Predict Motor Outcomes in Stroke: A Narrative Review.DOCX

Stroke is a leading cause of disability worldwide. Motor impairments occur in most of the patients with stroke in the acute phase and contribute substantially to disability. Diffusion tensor imaging (DTI) biomarkers such as fractional anisotropy (FA) measured at an early phase after stroke have emerged as potential predictors of motor recovery. In this narrative review, we: (1) review key concepts of diffusion MRI (dMRI); (2) present an overview of state-of-art methodological aspects of data collection, analysis and reporting; and (3) critically review challenges of DTI in stroke as well as results of studies that investigated the correlation between DTI metrics within the corticospinal tract and motor outcomes at different stages after stroke. We reviewed studies published between January, 2008 and December, 2018, that reported correlations between DTI metrics collected within the first 24 h (hyperacute), 2–7 days (acute), and >7–90 days (early subacute) after stroke. Nineteen studies were included. Our review shows that there is no consensus about gold standards for DTI data collection or processing. We found great methodological differences across studies that evaluated DTI metrics within the corticospinal tract. Despite heterogeneity in stroke lesions and analysis approaches, the majority of studies reported significant correlations between DTI biomarkers and motor impairments. It remains to be determined whether DTI results could enhance the predictive value of motor disability models based on clinical and neurophysiological variables.

脑卒中是全球范围内导致残疾的首要病因。多数卒中患者在急性期会出现运动功能障碍，该障碍是导致患者残疾的重要因素。卒中后早期阶段检测得到的弥散张量成像（diffusion tensor imaging, DTI）生物标志物（如各向异性分数（fractional anisotropy, FA））已被证实为运动功能恢复的潜在预测指标。在本叙述性综述中，我们：（1）回顾了弥散磁共振成像（diffusion magnetic resonance imaging, dMRI）的核心概念；（2）概述了数据采集、分析与报告的前沿方法学要点；（3）批判性评述了卒中领域中弥散张量成像面临的挑战，以及探究卒中后不同阶段皮质脊髓束内弥散张量成像指标与运动结局相关性的研究成果。

我们检索了2008年1月至2018年12月发表的相关研究，这些研究均报道了卒中后24小时内（超急性期）、2~7天（急性期）以及7~90天（早期亚急性期）采集的弥散张量成像指标间的相关性，最终纳入19项研究。

本综述结果显示，目前学界尚未就弥散张量成像数据采集与处理的金标准达成共识；在评估皮质脊髓束内弥散张量成像指标的各项研究中，方法学差异显著。尽管卒中病灶与分析方法存在异质性，但绝大多数研究均报道了弥散张量成像生物标志物与运动功能障碍间存在显著相关性。目前仍有待明确的是，弥散张量成像结果能否提升基于临床及神经生理学变量构建的运动功能残疾预测模型的预测效能。