title: Navigator based respiratory gating during acquisition and preparation phases for proton liver spectroscopy at 3 T.
abstract: Proton magnetic resonance spectroscopy ((1)H MRS) enables the non-invasive investigation of the human liver; however, because of technical difficulties it is not regularly used for diagnosis of liver diseases in clinical routine. Breathing motion is one of the major challenges, as it decreases spectral quality and leads to misplacement of the spectroscopic voxel. To overcome this problem, real-time navigator gating for spectral acquisition and preparation steps (B0 shimming, water frequency determination, receiver gain optimization, and water suppression) combined with short TE , optimized first order projection based B0 shimming, water suppression, and inner-volume saturated point resolved spectroscopy (PRESS) at 3 T is suggested. Simultaneous lipid and trimethylamine quantification is demonstrated by means of phantom, volunteer, and representative patient measurements. Precise localization of the voxel despite respiratory motion, increased spectral quality (higher signal-to-noise ratio and reduced linewidth) compared with measurements without respiratory gating, and the possibility of acquiring data without additional subject instructions regarding breathing enable robust and accurate liver (1)H MRS measurements with this novel acquisition protocol.
authors.affiliation: Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland; Department of Psychiatry, Psychotherapy and Psychosomatics, Zurich University Hospital for Psychiatry, Zurich, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Hock
authors.forename: L
authors.initials: L
authors.lastname: Valkovič
authors.forename: A
authors.initials: A
authors.lastname: Geier
authors.forename: T
authors.initials: T
authors.lastname: Kuntzen
authors.forename: P
authors.initials: P
authors.lastname: Boesiger
authors.forename: A
authors.initials: A
authors.lastname: Henning
mesh_terms: D000465:Algorithms; D002794:Choline / Q000378:metabolism; D003199:Computer Systems; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008099:Liver / Q000473:pathology*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008954:Models, Biological; D019047:Phantoms, Imaging; D011522:Protons; D012119:Respiration
chemical_list: D011522:Protons; D002794:Choline
keywords: in vivo; liver; magnetic resonance spectroscopy; motion correction; navigator gating