Translating state-of-the-art spinal cord MRI techniques to clinical use: A systematic review of clinical studies utilizing DTI, MT, MWF, MRS, and fMRI.
Translating state-of-the-art spinal cord MRI techniques to clinical use: A systematic review of clinical studies utilizing DTI, MT, MWF, MRS, and fMRI.
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DOI：
10.1016/j.nicl.2015.11.019
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Fehlings MG
中科院分区：
文献类型：
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作者：
Martin AR;Aleksanderek I;Cohen-Adad J;Tarmohamed Z;Tetreault L;Smith N;Cadotte DW;Crawley A;Ginsberg H;Mikulis DJ;Fehlings MG
最近由国际脊髓研究信托基金（ISRT）和生命之翼基金会（Wings for Life Foundation）主办的国际成像专家会议确定了5种最先进的MRI技术，通过阐明微观结构和功能的要素，它们有可能改变脊髓成像领域：扩散张量成像（DTI）、磁化转移（MT）、髓磷脂水组分（MWF）、磁共振光谱（MRS）和功能磁共振成像（fMRI）。然而，这些技术在临床转化方面的进展尚未确定。使用MEDLINE、MEDLINE-in- progress、Embase和Cochrane数据库对英文文献进行了系统回顾，以确定所有在诊断、与残疾的相关性和结果预测方面调查这些有前途的技术在影响脊髓病理方面的效用的人类研究。有关研究设计、受试者特征、MRI方法、临床损伤测量和分析技术的数据被提取并制成表格，以确定趋势和共性。对这些研究进行偏倚风险评估，并使用分级建议评估、发展和评价（GRADE）框架对每个具体发现的总体证据质量进行评估。在数据库检索中共鉴定出6597条独特的引文，在对274篇文章进行全文审查后，共鉴定出104篇相关研究（97%来自初始数据库检索）。其中，69项研究使用了DTI， 25项研究使用了MT，这两种技术近年来的出版物数量都有所增加。该综述还确定了1项MWF研究，11项MRS研究和8项fMRI研究。大多数研究本质上是探索性的，缺乏先验假设，由于研究设计、获取技术和分析方法的问题，显示出高（72%）或中高（20%）的偏倚风险。在不同的研究中，每种技术获得的结果差异很大，这使得直接比较指标无效。DTI指标分数各向异性（FA）具有最强的实用性证据，有中等质量的证据表明其作为生物标志物与几种临床病理的残疾相关，与健康对照相比，它识别组织损伤的证据水平较低（就组差异而言）。然而，没有足够的证据来确定它作为一种敏感和特定的诊断测试或作为预测临床结果的工具的效用。极低质量的证据表明，与对照组相比，其他指标也显示出组间差异，包括DTI指标平均扩散率（MD）和径向扩散率（RD），扩散峰度成像（DKI）指标平均峰度（MK）， MT指标MT比（MTR）和MT脑脊液比（MTCSF），以及n -乙酰天冬氨酸（NAA）浓度的MRS指标，尽管这些结果有些不一致。最先进的脊髓MRI技术在改善各种脊髓病变的诊断和治疗方面具有巨大的潜力，但目前的证据仅显示有限的临床应用。在这些成像工具中，DTI是最成熟的，但在临床领域采用DTI之前，需要进一步的标准化和验证其使用。为了充分展示这些快速发展的技术的潜力，需要大规模、精心设计的研究，包括先验假设、标准化的获取方法、详细的临床数据收集和强大的自动化分析技术。
A recent meeting of international imaging experts sponsored by the International Spinal Research Trust (ISRT) and the Wings for Life Foundation identified 5 state-of-the-art MRI techniques with potential to transform the field of spinal cord imaging by elucidating elements of the microstructure and function: diffusion tensor imaging (DTI), magnetization transfer (MT), myelin water fraction (MWF), MR spectroscopy (MRS), and functional MRI (fMRI). However, the progress toward clinical translation of these techniques has not been established. A systematic review of the English literature was conducted using MEDLINE, MEDLINE-in-Progress, Embase, and Cochrane databases to identify all human studies that investigated utility, in terms of diagnosis, correlation with disability, and prediction of outcomes, of these promising techniques in pathologies affecting the spinal cord. Data regarding study design, subject characteristics, MRI methods, clinical measures of impairment, and analysis techniques were extracted and tabulated to identify trends and commonalities. The studies were assessed for risk of bias, and the overall quality of evidence was assessed for each specific finding using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework. A total of 6597 unique citations were identified in the database search, and after full-text review of 274 articles, a total of 104 relevant studies were identified for final inclusion (97% from the initial database search). Among these, 69 studies utilized DTI and 25 used MT, with both techniques showing an increased number of publications in recent years. The review also identified 1 MWF study, 11 MRS studies, and 8 fMRI studies. Most of the studies were exploratory in nature, lacking a priori hypotheses and showing a high (72%) or moderately high (20%) risk of bias, due to issues with study design, acquisition techniques, and analysis methods. The acquisitions for each technique varied widely across studies, rendering direct comparisons of metrics invalid. The DTI metric fractional anisotropy (FA) had the strongest evidence of utility, with moderate quality evidence for its use as a biomarker showing correlation with disability in several clinical pathologies, and a low level of evidence that it identifies tissue injury (in terms of group differences) compared with healthy controls. However, insufficient evidence exists to determine its utility as a sensitive and specific diagnostic test or as a tool to predict clinical outcomes. Very low quality evidence suggests that other metrics also show group differences compared with controls, including DTI metrics mean diffusivity (MD) and radial diffusivity (RD), the diffusional kurtosis imaging (DKI) metric mean kurtosis (MK), MT metrics MT ratio (MTR) and MT cerebrospinal fluid ratio (MTCSF), and the MRS metric of N-acetylaspartate (NAA) concentration, although these results were somewhat inconsistent. State-of-the-art spinal cord MRI techniques are emerging with great potential to improve the diagnosis and management of various spinal pathologies, but the current body of evidence has only showed limited clinical utility to date. Among these imaging tools DTI is the most mature, but further work is necessary to standardize and validate its use before it will be adopted in the clinical realm. Large, well-designed studies with a priori hypotheses, standardized acquisition methods, detailed clinical data collection, and robust automated analysis techniques are needed to fully demonstrate the potential of these rapidly evolving techniques.