title: Simultaneous PET-MR acquisition and MR-derived motion fields for correction of non-rigid motion in PET.
abstract: OBJECTIVE
  Positron emission tomography (PET) provides an accurate measurement of radiotracer concentration in vivo, but performance can be limited by subject motion which degrades spatial resolution and quantitative accuracy. This effect may become a limiting factor for PET studies in the body as PET scanner technology improves. In this work, we propose a new approach to address this problem by employing motion information from images measured simultaneously using a magnetic resonance (MR) scanner.
  
  
  METHODS
  The approach is demonstrated using an MR-compatible PET scanner and PET-MR acquisition with a purpose-designed phantom capable of non-rigid deformations. Measured, simultaneously acquired MR data were used to correct for motion in PET, and results were compared with those obtained using motion information from PET images alone.
  
  
  RESULTS
  Motion artefacts were significantly reduced and the PET image quality and quantification was significantly improved by the use of MR motion fields, whilst the use of PET-only motion information was less successful.
  
  
  CONCLUSIONS
  Combined PET-MR acquisitions potentially allow PET motion compensation in whole-body acquisitions without prolonging PET acquisition time or increasing radiation dose. This, to the best of our knowledge, is the first study to demonstrate that simultaneously acquired MR data can be used to estimate and correct for the effects of non-rigid motion in PET.
authors.affiliation: Division of Imaging Sciences, King's College London, 4th Floor Lambeth Wing, St. Thomas' Hospital, Westminster Bridge Rd, London, SE1 7EH, UK. Charalampos.Tsoumpas@kcl.ac.uk
authors.forename: Charalampos
authors.initials: C
authors.lastname: Tsoumpas
authors.forename: Jane E
authors.initials: JE
authors.lastname: Mackewn
authors.forename: Philip
authors.initials: P
authors.lastname: Halsted
authors.forename: Andrew P
authors.initials: AP
authors.lastname: King
authors.forename: Christian
authors.initials: C
authors.lastname: Buerger
authors.forename: John J
authors.initials: JJ
authors.lastname: Totman
authors.forename: Tobias
authors.initials: T
authors.lastname: Schaeffter
authors.forename: Paul K
authors.initials: PK
authors.lastname: Marsden
mesh_terms: D016477:Artifacts; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D009068:Movement; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation / Q000379:methods*; D013997:Time Factors