title: MRI by steering resonance through space.
abstract: OBJECTIVE
  This work introduces a technique to excite MR signals locally and to steer this localized region over the object in a spatiotemporal manner. The purpose is to demonstrate the feasibility of MRI with multidimensional spatiotemporal-encoding in a way that provides the ability to compensate extreme field inhomogeneity.
  
  
  METHODS
  The method is called steering resonance over the object (STEREO). A modulated gradient is applied in concert with a frequency-modulated pulse to steer a resonant region through space and thus produce sequential excitation and echo formation. Images are reconstructed using exclusively an inverse problem solution.
  
  
  RESULTS
  Images of phantoms and human brain were produced to demonstrate the feasibility of the STEREO sequence and image reconstruction. Simulations support the postulated capability to compensate for extreme field inhomogeneity.
  
  
  CONCLUSIONS
  STEREO represents a substantial departure from conventional MRI in which spins contained in the sample, slab, or slice are excited synchronously. By exciting spins sequentially along a curved spatial trajectory, STEREO in principle affords a unique opportunity to adjust for spatial variations in static and radiofrequency fields. By adjusting field amplitudes and frequencies in a temporal manner in STEREO, in future works it should be possible to perform MRI with highly inhomogeneous fields.
authors.affiliation: Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota School of Medicine, Minneapolis, Minnesota, USA.
authors.forename: Angela L S
authors.initials: AL
authors.lastname: Snyder
authors.forename: Curtis A
authors.initials: CA
authors.lastname: Corum
authors.forename: Steen
authors.initials: S
authors.lastname: Moeller
authors.forename: Nathaniel J
authors.initials: NJ
authors.lastname: Powell
authors.forename: Michael
authors.initials: M
authors.lastname: Garwood
mesh_terms: D016477:Artifacts; D001931:Brain Mapping / Q000379:methods*; D005240:Feasibility Studies; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging
keywords: MRI methodologies; field inhomogeneities; spatial encoding
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