Verma Gaurav, Hariharan Hari, Nagarajan Rajakumar, Nanga Ravi P R, Delikatny Edward J, Albert Thomas M, Poptani Harish
Department of Radiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
J Magn Reson Imaging. 2014 Dec;40(6):1319-27. doi: 10.1002/jmri.24510. Epub 2013 Nov 22.
To evaluate the utility of two-dimensional (2D) Localized Correlated Spectroscopy (L-COSY) in metabolic profiling of the human brain at 7 Tesla (T).
The 2D L-COSY sequence was implemented at 7 T and its reliability was assessed by test-retest studies of a metabolite phantom and a healthy volunteer. L-COSY data were acquired from the occipital lobe of healthy subjects (n = 6; all male; age, 30-72 years) to assess intersubject variability. Additionally, two subjects underwent scans from the parieto-occipital region, basal ganglia, frontal lobe or dorsolateral prefrontal cortex to test the versatility of L-COSY in studying differing anatomy. Integral/volume measurements of L-COSY spectra were used to estimate normalized metabolite-to-creatine concentrations.
Phantom test-retest studies revealed coefficients of variation (CVs) of 3-20% for most metabolites. Human 2D L-COSY spectra permitted detection of several metabolite resonances from multiple locations and inter-subject variation studies demonstrated CVs of 4-26%. Cross-peaks from gamma-aminobutyric acid (GABA), isoleucine (Ile), lysine (Lys) and Ethanolamine (Eth) were quantified, which are not readily resolvable with conventional one-dimensional (1D) MR spectroscopy.
2D L-COSY at 7 T demonstrated improved sensitivity in detecting additional metabolites with reliability comparable to established techniques at lower fields, which may aid in the metabolic assessment of diseased states.
评估二维（2D）局部相关光谱法（L-COSY）在7特斯拉（T）场强下对人脑进行代谢谱分析的效用。
在7T场强下实施二维L-COSY序列，并通过对代谢物模型和一名健康志愿者进行重测研究来评估其可靠性。从健康受试者（n = 6；均为男性；年龄30 - 72岁）的枕叶采集L-COSY数据，以评估个体间变异性。此外，两名受试者接受了来自顶枕区、基底神经节、额叶或背外侧前额叶皮质的扫描，以测试L-COSY在研究不同解剖结构方面的通用性。L-COSY谱的积分/体积测量用于估计代谢物与肌酸的标准化浓度。
模型重测研究显示，大多数代谢物的变异系数（CV）为3% - 20%。人体二维L-COSY谱能够检测到多个位置的几种代谢物共振峰，个体间变异研究显示CV为4% - 26%。对γ-氨基丁酸（GABA）、异亮氨酸（Ile）、赖氨酸（Lys）和乙醇胺（Eth）的交叉峰进行了定量分析，这些在传统一维（1D）磁共振波谱中不易分辨。
7T场强下的二维L-COSY在检测更多代谢物方面显示出更高的灵敏度，其可靠性与低场强下的现有技术相当，这可能有助于对疾病状态进行代谢评估。
