MRS fitting challenge data setup by ISMRM MRS study group

Fitting of the magnetic resonance spectroscopy (MRS) data plays an important role in the quantification of metabolite concentrations. A number of commercial and home-built packages are available and used by the MRS community to fit spectra. The question arose whether any one of these packages was superior to the others or whether they all perform similarly if appropriately used. Hence, in preparation for a workshop of the ISMRM MRS study group on MR Spectroscopy: from Current Best Practice to Latest Frontiers, which took place in August 2016, it was decided by the organizing committee, that this question should be tackled by a fitting challenge open to everybody, where a set of spectra would be evaluated.
For this purpose, synthetic MRS data were generated for 28 datasets. Short-echo time PRESS spectra were simulated using ideal pulses for the common metabolites at mostly near-normal brain concentrations. A macromolecular contribution was also included. Modulations of signal-to-noise ratio (SNR), lineshape type and width, concentrations of γ-aminobutyric acid, glutathione and macromolecules, and inclusion of artifacts and lipid signals to mimic tumor spectra were included as challenges to be coped with.

磁共振波谱（Magnetic Resonance Spectroscopy, MRS）数据的拟合操作，在代谢物浓度定量分析中发挥着关键作用。当前磁共振波谱学界已拥有多款商用及自研软件包，用于谱线拟合任务。此前学界曾提出一个核心疑问：在正确使用的前提下，这些软件包中是否存在性能更优的个体，抑或所有工具的表现均无显著差异？为解答该问题，在筹备2016年8月举办的国际磁共振医学学会（International Society for Magnetic Resonance in Medicine, ISMRM）磁共振波谱研究小组研讨会（主题为"从当前最佳实践到前沿进展"）期间，组织委员会决定发起一项面向所有研究者的拟合挑战赛，通过对一组谱数据的评估来验证该疑问。本次挑战赛共生成28组合成MRS数据。针对常见脑内代谢物，研究团队采用理想脉冲模拟了短回波时间PRESS谱，代谢物浓度大多设置为接近正常的脑内水平，同时还加入了大分子信号分量。挑战赛设置了多类考核挑战：包括调整信噪比（Signal-to-Noise Ratio, SNR）、谱线形状与线宽，改变γ-氨基丁酸（γ-aminobutyric acid）、谷胱甘肽及大分子的浓度，以及加入伪影与脂质信号以模拟肿瘤谱场景等。