title: Single-scan MRI with exceptional resilience to field heterogeneities.
abstract: Single-scan two-dimensional MRI has been generally constrained to acquisitions in high quality magnets. This study introduces a methodology, cross-term spatiotemporal encoding (xSPEN), that delivers such images under much poorer external field conditions.
  
  
  
  xSPEN departs from conventional k-space scanning, by relying on spatiotemporally encoding the image being sought. Unlike hitherto proposed SPEN methods, however, xSPEN's image readout does not take place using a field gradient along the direction being probed, but rather with the aid of an ancillary source of inhomogeneous frequency broadening. This ancillary dimension was here imposed by an orthogonal field gradient; for example, images along the "y" axis were read out by application of a "z" gradient. The principles and characteristics of this new approach, compatible with existing scanners and free from the need to collect auxiliary information such as field maps, are presented and discussed.
  
  
  
  Single- and multi-slice in vitro, ex vivo, and in vivo MRI experiments, confirmed the unusual resilience of this new single-shot MRI method to multiple chemical sites on phantoms, animals and humans.
  
  
  
  xSPEN can deliver single-scan MRI with good sensitivity and exceptional resilience to field inhomogeneities. This could enable investigations that have hitherto escaped from MRI's scope. Magn Reson Med 77:623-634, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel.|Department of Electronic Science, Fujian Provincial Key Laboratory of Plasma and Magnetic Resonance, Xiamen University, Xiamen, Fujian, China.
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Amir
authors.initials: A
authors.lastname: Seginer
authors.affiliation: Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel.
authors.forename: Lucio
authors.initials: L
authors.lastname: Frydman
mesh_terms: D000818:Animals; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D051381:Rats; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: cross-term SPEN; echo-planar imaging; spatiotemporal encoding; ultrafast MRI acquisitions