title: Refined modelling of the short-T2 signal component and ensuing detection of glutamate and glutamine in short-TE, localised, (1) H MR spectra of human glioma measured at 3 T.
abstract: Short-TE (1) H MRS has great potential for brain cancer diagnostics. A major difficulty in the analysis of the spectra is the contribution from short-T2 signal components, mainly coming from mobile lipids. This complicates the accurate estimation of the spectral parameters of the resonance lines from metabolites, so that a qualitative to semi-quantitative interpretation of the spectra dominates in practice. One solution to overcome this difficulty is to measure and estimate the short-T2 signal component and to subtract it from the total signal, thus leaving only the metabolite signals. The technique works well when applied to spectra obtained from healthy individuals, but requires some optimisation during data acquisition. In the clinical setting, time constraints hardly allow this. Here, we propose an iterative estimation of the short-T2 signal component, acquired in a single acquisition after measurement of the full spectrum. The method is based on QUEST (quantitation based on quantum estimation) and allows the refinement of the estimate of the short-T2 signal component after measurement. Thus, acquisition protocols used on healthy volunteers can also be used on patients without further optimisation. The aim is to improve metabolite detection and, ultimately, to enable the estimation of the glutamine and glutamate signals distinctly. These two metabolites are of great interest in the characterisation of brain cancer, gliomas in particular. When applied to spectra from healthy volunteers, the new algorithm yields similar results to QUEST and direct subtraction of the short-T2 signal component. With patients, up to 12 metabolites and, at least, seven can be quantified in each individual brain tumour spectrum, depending on the metabolic state of the tumour. The refinement of the short-T2 signal component significantly improves the fitting procedure and produces a separate short-T2 signal component that can be used for the analysis of mobile lipid resonances. Thus, in brain tumour spectra, distinct estimates of signals from glutamate and glutamine are possible. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Lund University Bioimaging Center, Lund, Sweden.
authors.forename: Michael
authors.initials: M
authors.lastname: Gottschalk
authors.affiliation: Univ. Grenoble Alpes, IRMaGe, CNRS, UMR 3552, INSERM, US17 and CLUNI, CHU de Grenoble, IRMaGe, F-38000, Grenoble, France.
authors.forename: Irène
authors.initials: I
authors.lastname: Troprès
authors.affiliation: Univ. Grenoble Alpes, IRMaGe, CNRS, UMR 3552, INSERM, US17 and CLUNI, CHU de Grenoble, IRMaGe, F-38000, Grenoble, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Lamalle
authors.affiliation: Université des Alpes Grenoble 1, Grenoble Institut des Neurosciences, Equipe 5, Clinique Universitaire de Neuroradiologie et IRM (CLUNI) and Centre Hospitalier Universitaire de Grenoble et des Alpes (CHUGA), Grenoble, France.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Grand
authors.affiliation: Université des Alpes Grenoble 1, Grenoble Institut des Neurosciences, Equipe 5, Clinique Universitaire de Neuroradiologie et IRM (CLUNI) and Centre Hospitalier Universitaire de Grenoble et des Alpes (CHUGA), Grenoble, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Le Bas
authors.affiliation: Grenoble Institut des Neurosciences, Grenoble, France.
authors.forename: Christoph
authors.initials: C
authors.lastname: Segebarth
mesh_terms: D000328:Adult; D000465:Algorithms; D014408:Biomarkers, Tumor / Q000378:metabolism*; D001932:Brain Neoplasms / Q000378:metabolism*; D003198:Computer Simulation; D005260:Female; D005910:Glioma / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D008956:Models, Chemical; D066244:Proton Magnetic Resonance Spectroscopy / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
chemical_list: D014408:Biomarkers, Tumor; D005973:Glutamine; D018698:Glutamic Acid
keywords: glioma; glutamine; head and neck cancer < cancer < applications; human study < cancer < applications; lipid and macromolecular baseline; spectroscopic quantitation < MR spectroscopy (MRS) and spectroscopic imaging (MRSI) methods < methods and engineering