title: B1 and T1 insensitive water and lipid suppression using optimized multiple frequency-selective preparation pulses for whole-brain 1H spectroscopic imaging at 3T.
abstract: A new method for the simultaneous suppression of water and lipid resonances using a series of dual-band frequency-selective radiofrequency (RF) pulses with associated dephasing gradients is presented. By optimizing the nutation angles of the individual pulses, the water and lipid suppression is made insensitive to a range of both T1-relaxation times and B1 inhomogeneities. The method consists only of preparatory RF pulses and thus can be combined with a wide variety of MRSI schemes including both long and short TE studies. Simulations yield suppression factors, in the presence of +/-20% B1 inhomogeneity, on the order of 100 for lipid peaks with three different T1s (300 ms, 310 ms, and 360 ms), and water peaks with T1s ranging from 0.8 s to 4 s. Excellent in vivo study performance is demonstrated using a 3 Tesla volumetric proton spectroscopic imaging (1H-MRSI) sequence for measuring the primary brain metabolites peaks of choline (Cho), creatine (Cr), and N-acetyl aspartate (NAA).
authors.affiliation: Department of Electrical Engineering, Stanford University, Stanford, California 94305-5488, USA. mgu@stanford.edu
authors.forename: Meng
authors.initials: M
authors.lastname: Gu
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Spielman
mesh_terms: D000465:Algorithms; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000032:analysis; D001921:Brain / Q000033:anatomy & histology / Q000378:metabolism*; D002794:Choline / Q000032:analysis*; D003401:Creatine / Q000032:analysis*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008055:Lipids / Q000032:analysis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011522:Protons; D014018:Tissue Distribution; D014867:Water / Q000032:analysis*
chemical_list: D008055:Lipids; D011522:Protons; D014867:Water; D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline