title: Alleviating artifacts in 1H MRI thermometry by single scan spatiotemporal encoding.
abstract: OBJECTIVE
  Recent years have seen an increased interest in combining MRI thermometry with devices capable of destroying malignancies by heat ablation. Expected from the MR protocols are accurate and fast thermal characterizations, providing real time feedback on restricted tissue volumes and/or rapidly moving organs like liver. This article explores the potential advantages of relying on spatiotemporally encoded (SPEN) sequences for retrieving real-time thermometric images based on the water's proton resonance frequency (PRF) shifts.
  
  
  METHODS
  Hybrid spatiotemporal/k-space encoding single-scan MRI experiments were implemented on animal and human scanners, and their abilities to deliver single- and multi-slice real-time thermometric measurements based on PRF-derived phase maps in phantoms and in vivo, were compared against echo planar imaging (EPI) and gradient-echo counterparts.
  
  
  RESULTS
  Under comparable acquisition conditions, SPEN exhibited advantages vis-à-vis EPI in terms of dealing with inhomogeneous magnetic field distortions, with shifts arising due to changes in the central frequency offsets, with PRF distributions, and for zooming into restricted fields-of-view without special pulse sequence provisions.
  
  
  CONCLUSIONS
  This work confirms the ability of SPEN sequences, particularly when implemented under fully-refocused conditions, to exploit their built-in robustness to shift- and field-derived inhomogeneities for monitoring thermal changes in real-time under in vitro and in vivo conditions.
authors: Chemical Physics Department, Weizmann Institute of Science, 76100, Rehovot, Israel.
authors: Rita
authors: R
authors: Schmidt
authors: Lucio
authors: L
authors: Frydman
mesh_terms: D000818:Animals; D016477:Artifacts; D002645:Chickens; D017352:Echo-Planar Imaging / Q000379:methods; D006358:Hot Temperature; D006801:Humans; D006979:Hyperthermia, Induced / Q000379:methods; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional / Q000379:methods; D008099:Liver / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D019047:Phantoms, Imaging; D011522:Protons; D013696:Temperature; D062125:Thermometry / Q000379:methods*; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D011522:Protons; D014867:Water