title: Measurement and correction of microscopic head motion during magnetic resonance imaging of the brain.
abstract: Magnetic resonance imaging (MRI) is a widely used method for non-invasive study of the structure and function of the human brain. Increasing magnetic field strengths enable higher resolution imaging; however, long scan times and high motion sensitivity mean that image quality is often limited by the involuntary motion of the subject. Prospective motion correction is a technique that addresses this problem by tracking head motion and continuously updating the imaging pulse sequence, locking the imaging volume position and orientation relative to the moving brain. The accuracy and precision of current MR-compatible tracking systems and navigator methods allows the quantification and correction of large-scale motion, but not the correction of very small involuntary movements in six degrees of freedom. In this work, we present an MR-compatible tracking system comprising a single camera and a single 15 mm marker that provides tracking precision in the order of 10 m and 0.01 degrees. We show preliminary results, which indicate that when used for prospective motion correction, the system enables improvement in image quality at both 3 T and 7 T, even in experienced and cooperative subjects trained to remain motionless during imaging. We also report direct observation and quantification of the mechanical ballistocardiogram (BCG) during simultaneous MR imaging. This is particularly apparent in the head-feet direction, with a peak-to-peak displacement of 140 m.
authors.affiliation: Department of Radiology, University Medical Center Freiburg, Freiburg, Germany. julian.maclaren@uniklinik-freiburg.de
authors.forename: Julian
authors.initials: J
authors.lastname: Maclaren
authors.forename: Brian S R
authors.initials: BS
authors.lastname: Armstrong
authors.forename: Robert T
authors.initials: RT
authors.lastname: Barrows
authors.forename: K A
authors.initials: KA
authors.lastname: Danishad
authors.forename: Thomas
authors.initials: T
authors.lastname: Ernst
authors.forename: Colin L
authors.initials: CL
authors.lastname: Foster
authors.forename: Kazim
authors.initials: K
authors.lastname: Gumus
authors.forename: Michael
authors.initials: M
authors.lastname: Herbst
authors.forename: Ilja Y
authors.initials: IY
authors.lastname: Kadashevich
authors.forename: Todd P
authors.initials: TP
authors.lastname: Kusik
authors.forename: Qiaotian
authors.initials: Q
authors.lastname: Li
authors.forename: Cris
authors.initials: C
authors.lastname: Lovell-Smith
authors.forename: Thomas
authors.initials: T
authors.lastname: Prieto
authors.forename: Peter
authors.initials: P
authors.lastname: Schulze
authors.forename: Oliver
authors.initials: O
authors.lastname: Speck
authors.forename: Daniel
authors.initials: D
authors.lastname: Stucht
authors.forename: Maxim
authors.initials: M
authors.lastname: Zaitsev
mesh_terms: D002138:Calibration; D019416:Head Movements; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods; D059906:Neuroimaging / Q000295:instrumentation* / Q000379:methods; D012984:Software