Magnetic Resonance Research Center, Yale University, New Haven, CT, USA; Department of Radiology & Biomedical Imaging, Yale University, New Haven, CT, USA.
Magnetic Resonance Research Center, Yale University, New Haven, CT, USA; Department of Radiology & Biomedical Imaging, Yale University, New Haven, CT, USA; Department of Biomedical Engineering, Yale University, New Haven, CT, USA.
Neuroimage. 2019 Jan 1;184:101-108. doi: 10.1016/j.neuroimage.2018.09.008. Epub 2018 Sep 8.
While functional MRI (fMRI) localizes regions of brain activation, functional MRS (fMRS) provides insights into metabolic underpinnings. Previous fMRS studies detected task-induced lactate increase using short echo-time non-edited H-MRS protocols, where lactate changes depended on accurate exclusion of overlapping lactate and lipid/macromolecule signals. Because long echo-time J-difference H-MRS detection of lactate is less susceptible to this shortcoming, we posited if J-edited fMRS protocol could reliably detect metabolic changes in the human motor cortex during a finger-tapping paradigm in relation to a reliable measure of basal lactate. Our J-edited fMRS protocol at 4T was guided by an fMRI pre-scan to determine the H-MRS voxel placement in the motor cortex. Because lactate and β-hydroxybutyrate (BHB) follow similar J-evolution profiles we observed both metabolites in all spectra, but only lactate showed reproducible task-induced modulation by 0.07 mM from a basal value of 0.82 mM. These J-edited fMRS results demonstrate good sensitivity and specificity for task-induced lactate modulation, suggesting that J-edited fMRS studies can be used to investigate the metabolic underpinning of human cognition by measuring lactate dynamics associated with activation and deactivation fMRI paradigms across brain regions at magnetic field lower than 7T.
虽然功能磁共振成像 (fMRI) 可以定位大脑激活区域，但功能磁共振波谱 (fMRS) 可以深入了解代谢基础。先前的 fMRS 研究使用短回波时间非编辑 H-MRS 方案检测任务诱导的乳酸增加，其中乳酸变化取决于准确排除重叠的乳酸和脂质/大分子信号。由于长回波时间 J 差 H-MRS 检测乳酸受此缺点的影响较小，因此我们假设 J 编辑 fMRS 方案是否可以可靠地检测到手指敲击范式中人类运动皮层的代谢变化与可靠的基础乳酸测量值相关。我们在 4T 下的 J 编辑 fMRS 方案通过 fMRI 预扫描来确定运动皮层中 H-MRS 体素的位置。由于乳酸和 β-羟基丁酸 (BHB) 遵循相似的 J 演变曲线，我们在所有光谱中都观察到这两种代谢物，但只有乳酸在基础值为 0.82mM 的情况下显示出可重复的任务诱导调制，调制幅度为 0.07mM。这些 J 编辑 fMRS 结果表明，任务诱导的乳酸调制具有良好的灵敏度和特异性，表明 J 编辑 fMRS 研究可以通过测量与激活和去激活 fMRI 范式相关的乳酸动力学，用于研究磁场低于 7T 的脑区人类认知的代谢基础。
