title: Rapid multi-echo measurement of brain metabolite T₂ values at 7 T using a single-shot spectroscopic Carr-Purcell-Meiboom-Gill sequence and prior information.
abstract: We present a method for the robust and accurate estimation of brain metabolite transverse relaxation times (T2 ) from multiple spin-echo data acquired with a single-shot Carr-Purcell-Meiboom-Gill (CPMG) spectroscopic sequence. Each acquired echo consists of a small number of complex time-domain data points. The amplitudes of the spectral components in each echo are calculated by solving a set of linear equations in which previously estimated frequencies and linewidths serve as prior information. These priors are obtained from a short MRS experiment in which a large number of time-domain data points are acquired, and are subsequently estimated using linear prediction with singular value decomposition (LPSVD) processing. We show that this process can be used to accurately and rapidly measure the T2 values for the main singlet resonances in single-volume MRS measurements in the brain. The proposed method can be generalized to any set of MRS experiments comprising repeated measurements of amplitude changes, e.g. as a function of an experimental parameter, such as TE, inversion time or diffusion weighting.
authors.affiliation: C. J. Gorter Center for High Field MRI Research, Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands.
authors.forename: Itamar
authors.initials: I
authors.lastname: Ronen
authors.forename: Ece
authors.initials: E
authors.lastname: Ercan
authors.forename: Andrew
authors.initials: A
authors.lastname: Webb
mesh_terms: D000328:Adult; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D002794:Choline / Q000378:metabolism; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D055442:Metabolome; D010725:Phosphocreatine / Q000378:metabolism; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors
chemical_list: D010725:Phosphocreatine; D001224:Aspartic Acid; C000179:N-acetylaspartate; D002794:Choline
keywords: MRS; brain metabolites; relaxation times