Human Brain: Proton Diffusion MR Spectroscopy’

Diffusion of brain metabolites was measured in 10 healthy volunteers by using localized proton diffusion mag-netic resonance (MR) spectroscopy. Measurements were conducted with a clinical MR imager by using a stim-ulated-echo pulse sequence (3,000/60 [repetition time msec/echo time msecl, 200-msec mixing time) with additional outside-volume suppres-sion. Motion artifacts due to macro-scopic brain movements were com-pensated by means of peripheral cardiac gating and separate collection of individual spectroscopic acquisi-tions into a two-dimensional data matrix. Phase errors due to macro-scopic motion were subsequently cor-rected in individual data traces prior to spectral averaging. Mean (±1 stan-dard deviation) apparent diffusion coefficients of choline-containing compounds ([0.13 ± 0.031 x i0 ii.n2/ sec), creatine and phosphocreatine ([0.15 ± 0.03] x iO mm2!sec), and N-acetyl aspartate ([0.18 ± 0.02J x iO mm2,/sec) were substantially smaller than that of water and were consis-tent with recently published data ob-tamed in anesthetized and paralyzed animals. Adequate diffusion sensi-tivity for metaboiites in the human brain can be obtained with clinical whole-body imagers despite macro-scopic head and brain movements