title: Comparison of longitudinal metabolite relaxation times in different regions of the human brain at 1.5 and 3 Tesla.
abstract: In vivo longitudinal relaxation times of N-acetyl compounds (NA), choline-containing substances (Cho), creatine (Cr), myo-inositol (mI), and tissue water were measured at 1.5 and 3 T using a point-resolved spectroscopy (PRESS) sequence with short echo time (TE). T(1) values were determined in six different brain regions: the occipital gray matter (GM), occipital white matter (WM), motor cortex, frontoparietal WM, thalamus, and cerebellum. The T(1) relaxation times of water protons were 26-38% longer at 3 T than at 1.5 T. Significantly longer metabolite T(1) values at 3 T (11-36%) were found for NA, Cho, and Cr in the motor cortex, frontoparietal WM, and thalamus. The amounts of GM, WM, and cerebrospinal fluid (CSF) within the voxel were determined by segmentation of a 3D image data set. No influence of tissue composition on metabolite T(1) values was found, while the longitudinal relaxation times of water protons were strongly correlated with the relative GM content.
authors.affiliation: Section of Experimental MR of the CNS, Department of Neuroradiology, University of Tuebingen, Tuebingen, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Ethofer
authors.forename: Irina
authors.initials: I
authors.lastname: Mader
authors.forename: Uwe
authors.initials: U
authors.lastname: Seeger
authors.forename: Gunther
authors.initials: G
authors.lastname: Helms
authors.forename: Michael
authors.initials: M
authors.lastname: Erb
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Grodd
authors.forename: Albert
authors.initials: A
authors.lastname: Ludolph
authors.forename: Uwe
authors.initials: U
authors.lastname: Klose
mesh_terms: D000328:Adult; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000032:analysis; D001923:Brain Chemistry; D002531:Cerebellum / Q000737:chemistry; D002794:Choline / Q000032:analysis; D003401:Creatine / Q000032:analysis; D005260:Female; D005625:Frontal Lobe / Q000737:chemistry; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D009044:Motor Cortex / Q000737:chemistry; D009778:Occipital Lobe / Q000737:chemistry; D010296:Parietal Lobe / Q000737:chemistry; D013788:Thalamus / Q000737:chemistry
chemical_list: D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline