HUMAN BRAIN - PROTON DIFFUSION MR SPECTROSCOPY

Diffusion of brain metabolites was measured in 10 healthy volunteers by using localized proton diffusion magnetic resonance (MR) spectroscopy. Measurements were conducted with a clinical MR imager by using a stimulated-echo pulse sequence (3,000/60 [repetition time msec/echo time msec], 200-msec mixing time) with additional outside-volume suppression. Motion artifacts due to macroscopic brain movements were compensated by means of peripheral cardiac gating and separate collection of individual spectroscopic acquisitions into a two-dimensional data matrix. Phase errors due to macroscopic motion were subsequently corrected in individual data traces prior to spectral averaging. Mean (+/- 1 standard deviation) apparent diffusion coefficients of choline-containing compounds ([0.13 +/- 0.03] x 10(-3) mm2/sec), creatine and phosphocreatine ([0.15 +/- 0.03] x 10(-3) mm2/sec), and N-acetyl aspartate ([0.18 +/- 0.02] x 10(-3) mm2/sec) were substantially smaller than that of water and were consistent with recently published data obtained in anesthetized and paralyzed animals. Adequate diffusion sensitivity for metabolites in the human brain can be obtained with clinical whole-body imagers despite macroscopic head and brain movements.