MRS

MRS
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    文章类型: Journal Article
    最近的专家共识发现,MRS研究中的非标准报告导致可重复性差。为了解决这个问题,引入了MRSinMRS指南;然而,由于不同的术语和数据格式,收养速度很慢。为了解决这个问题,REMY,支持主要供应商格式的工具箱,被创造了。通过有效地填充MRSinMRS表中的重要字段,它提高了可重复性。即使有某些与硬件相关的限制,REMY为完成采集参数做出了重大贡献,这有利于报告。它的兼容性和用户友好的界面应该促进MRSinMRS的广泛采用,提高MRS研究的口径。
    Recent expert consensus publications have highlighted the issue of poor reproducibility in magnetic resonance spectroscopy (MRS) studies, mainly due to the lack of standardized reporting criteria, which affects their clinical applicability. To combat this, guidelines for minimum reporting standards (MRSinMRS) were introduced to aid journal editors and reviewers in ensuring the comprehensive documentation of essential MRS study parameters. Despite these efforts, the implementation of MRSinMRS standards has been slow, attributed to the diverse nomenclature used by different vendors, the variety of raw MRS data formats, and the absence of appropriate software tools for identifying and reporting necessary parameters. To overcome this obstacle, we have developed the REproducibility Made Easy (REMY) standalone toolbox. REMY software supports a range of MRS data formats from major vendors like GE (p. file), Siemens (twix, .rda, .dcm), Philips (.spar/.sdat), and Bruker (.method), facilitating easy data import and export through a user-friendly interface. REMY employs external libraries such as spec2nii and pymapVBVD to accurately read and process these diverse data formats, ensuring compatibility and ease of use for researchers in generating reproducible MRS research outputs. Users can select and import datasets, choose the appropriate vendor and data format, and then generate an MRSinMRS table, log file, and methodological documents in both Latex and PDF formats. REMY effectively populated key sections of the MRSinMRS table with data from all supported file types. Accurate generation of hardware parameters including field strength, manufacturer, and scanner software version were demonstrated. However, it could not input data for RF coil and additional hardware information due to their absence in the files. For the acquisition section, REMY accurately read and populated fields for the pulse sequence name, nominal voxel size, repetition time (TR), echo time (TE), number of acquisitions/excitations/shots, spectral width [Hz], and number of spectral points, significantly contributing to the completion of the Acquisition fields of the table. Furthermore, REMY generates a boilerplate methods text section for manuscripts.The use of REMY will facilitate more widespread adoption of the MRSinMRS checklist within the MRS community, making it easier to write and report acquisition parameters effectively.
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  • 文章类型: Journal Article
    与MRI相比,由于固有的低信噪比和对高度均匀的B0场的需要而导致的长采集时间使得MRS特别容易受到运动或扫描仪不稳定性的影响。运动引起的定位和匀场变化(即B0均匀性)降低了MRS数据质量。为了减轻运动的影响,可以采用三种方法:(1)受试者固定,(2)回顾性校正,和(3)使用内部和/或外部跟踪方法的预期实时校正。前瞻性实时校正方法可以同时更新定位和B0场,以提高MRS数据质量。虽然定位错误可以通过内部(导航器)和外部(光学相机,核磁共振探头)跟踪方法,B0场校正需要内部导航器方法来测量成像体积内部的B0场,以及实时更新扫描仪垫片硬件的可能性。内部和外部跟踪可以快速更新亚毫米和亚度精度的MRS定位,而扫描仪频率和扫描仪硬件的一阶垫片可以通过每次序列重复的内部方法进行更新。这些方法在神经成像方面最为完善,刚性转换主要适用于此。实时校正大大提高了MRS采集和量化的稳定性,如对容易运动的受试者的临床研究所示,包括儿童和运动障碍患者,能够可靠地测量代谢物信号,包括低浓度的代谢物信号,如γ-氨基丁酸和谷胱甘肽。因此,建议MRS用户进行运动校正,并要求MR扫描仪制造商更紧密地集成和更广泛地使用此类方法。
    Long acquisition times due to intrinsically low signal-to-noise ratio and the need for highly homogeneous B0 field make MRS particularly susceptible to motion or scanner instability compared with MRI. Motion-induced changes in both localization and shimming (ie B0 homogeneity) degrade MRS data quality. To mitigate the effects of motion three approaches can be employed: (1) subject immobilization, (2) retrospective correction, and (3) prospective real-time correction using internal and/or external tracking methods. Prospective real-time correction methods can simultaneously update localization and the B0 field to improve MRS data quality. While localization errors can be corrected with both internal (navigators) and external (optical camera, NMR probes) tracking methods, the B0 field correction requires internal navigator methods to measure the B0 field inside the imaged volume and the possibility to update the scanner shim hardware in real time. Internal and external tracking can rapidly update the MRS localization with submillimeter and subdegree precision, while scanner frequency and first-order shims of scanner hardware can be updated by internal methods every sequence repetition. These approaches are most well developed for neuroimaging, for which rigid transformation is primarily applicable. Real-time correction greatly improves the stability of MRS acquisition and quantification, as shown in clinical studies on subjects prone to motion, including children and patients with movement disorders, enabling robust measurement of metabolite signals including those with low concentrations, such as gamma-aminobutyric acid and glutathione. Thus, motion correction is recommended for MRS users and calls for tighter integration and wider availability of such methods by MR scanner manufacturers.
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  • 文章类型: Journal Article
    一旦获取了MRS数据集,必须采取几个重要步骤来获得所需的代谢物浓度测量。首先,数据必须经过预处理,为分析做好准备。接下来,必须估计感兴趣的代谢物信号的强度。最后,必须使用定量参考信号将测量的代谢物信号强度转换为缩放浓度单位,以进行有意义的解释。在本文中,我们回顾了单体素MRS实验的采集后工作流程中的这三个主要步骤(预处理,分析和量化),并为每个步骤的最佳实践提供建议。
    Once an MRS dataset has been acquired, several important steps must be taken to obtain the desired metabolite concentration measures. First, the data must be preprocessed to prepare them for analysis. Next, the intensity of the metabolite signal(s) of interest must be estimated. Finally, the measured metabolite signal intensities must be converted into scaled concentration units employing a quantitative reference signal to allow meaningful interpretation. In this paper, we review these three main steps in the post-acquisition workflow of a single-voxel MRS experiment (preprocessing, analysis and quantification) and provide recommendations for best practices at each step.
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  • 文章类型: Journal Article
    质子MRS(1HMRS)提供非侵入性,组织的定量代谢物谱,并已被证明有助于几种脑疾病的临床管理。尽管大多数现代临床MR扫描仪支持MRS功能,常规使用在很大程度上仅限于获得MR研究支持的专业中心.广泛采用缓慢有几个原因,获得可靠的高质量结果的技术挑战已被确定为一个促成因素。研究界在解决许多这些挑战方面取得了相当大的进展,在本文中,就广泛可用的MRS方法的缺陷和目前在几个临床研究机构中常规使用的经过验证的改进提出了共识。特别是,发现PRESS定位序列的定位误差在3T时高得令人无法接受,并且通过绝热选择性重聚焦序列使用半绝热定位是推荐的解决方案。建议将模拟的代谢物基础集合并到分析例程中,以可靠地捕获从短TE采集中获得的完整光谱细节。此外,强调了在采集区域中实现高度均匀的静磁场(B0)的重要性,并讨论了现有方法和硬件的局限性。大多数建议只需要软件改进,大大提高了临床MRS在现有硬件上的能力。这些建议的实施应加强当前的临床应用,并在开发和验证用于临床的新的MRS生物标志物方面取得进展。
    Proton MRS (1 H MRS) provides noninvasive, quantitative metabolite profiles of tissue and has been shown to aid the clinical management of several brain diseases. Although most modern clinical MR scanners support MRS capabilities, routine use is largely restricted to specialized centers with good access to MR research support. Widespread adoption has been slow for several reasons, and technical challenges toward obtaining reliable good-quality results have been identified as a contributing factor. Considerable progress has been made by the research community to address many of these challenges, and in this paper a consensus is presented on deficiencies in widely available MRS methodology and validated improvements that are currently in routine use at several clinical research institutions. In particular, the localization error for the PRESS localization sequence was found to be unacceptably high at 3 T, and use of the semi-adiabatic localization by adiabatic selective refocusing sequence is a recommended solution. Incorporation of simulated metabolite basis sets into analysis routines is recommended for reliably capturing the full spectral detail available from short TE acquisitions. In addition, the importance of achieving a highly homogenous static magnetic field (B0 ) in the acquisition region is emphasized, and the limitations of current methods and hardware are discussed. Most recommendations require only software improvements, greatly enhancing the capabilities of clinical MRS on existing hardware. Implementation of these recommendations should strengthen current clinical applications and advance progress toward developing and validating new MRS biomarkers for clinical use.
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