title: Measurement and correction of respiration-induced B0 variations in breast 1H MRS at 4 Tesla.
abstract: Respiratory motion is well known to cause artifacts in magnetic resonance spectroscopy (MRS). In MRS of the breast, the dominant artifact is not due to motion of the breast itself, but rather it is produced by B0 field distortions associated with respiratory motion of tissues in the chest and abdomen. This susceptibility artifact has been reported to occur in the brain, but it is more apparent in the breast due to the anatomic proximity of the lungs. In the breast, these B0 distortions cause shot-to-shot frequency shifts, which vary an average of 24 Hz during a typical 1H MRS scan at 4 T. This variation can be corrected retrospectively by frequency shifting individual spectra prior to averaging. If not corrected, these shifts reduce spectral resolution and increase peak fitting errors. This work demonstrates the artifact, describes a method for correcting it, and evaluates its impact on quantitative spectroscopy. When the artifact is not corrected, quantification errors increase by an average of 28%, which dramatically impacts the ability to measure metabolite resonances at low signal-to-noise ratios.
authors.affiliation: Center for Magnetic Resonance Research, University of Minnesota School of Medicine, Minneapolis 55455, USA. bolan@cmrr.umn.edu
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Bolan
authors.forename: Pierre-Gilles
authors.initials: PG
authors.lastname: Henry
authors.forename: Eva H
authors.initials: EH
authors.lastname: Baker
authors.forename: Sina
authors.initials: S
authors.lastname: Meisamy
authors.forename: Michael
authors.initials: M
authors.lastname: Garwood
mesh_terms: D016477:Artifacts; D001941:Breast Diseases / Q000378:metabolism*; D002794:Choline / Q000378:metabolism; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D012119:Respiration; D012189:Retrospective Studies; D012815:Signal Processing, Computer-Assisted
chemical_list: D002794:Choline