title: 3D single point imaging with compressed sensing provides high temporal resolution R2* mapping for in vivo preclinical applications.
abstract: OBJECTIVE
  Purely phase-encoded techniques such as single point imaging (SPI) are generally unsuitable for in vivo imaging due to lengthy acquisition times. Reconstruction of highly undersampled data using compressed sensing allows SPI data to be quickly obtained from animal models, enabling applications in preclinical cellular and molecular imaging.
  
  
  METHODS
  TurboSPI is a multi-echo single point technique that acquires hundreds of images with microsecond spacing, enabling high temporal resolution relaxometry of large-R2* systems such as iron-loaded cells. TurboSPI acquisitions can be pseudo-randomly undersampled in all three dimensions to increase artifact incoherence, and can provide prior information to improve reconstruction. We evaluated the performance of CS-TurboSPI in phantoms, a rat ex vivo, and a mouse in vivo.
  
  
  RESULTS
  An algorithm for iterative reconstruction of TurboSPI relaxometry time courses does not affect image quality or R2* mapping in vitro at acceleration factors up to 10. Imaging ex vivo is possible at similar acceleration factors, and in vivo imaging is demonstrated at an acceleration factor of 8, such that acquisition time is under 1 h.
  
  
  CONCLUSIONS
  Accelerated TurboSPI enables preclinical R2* mapping without loss of data quality, and may show increased specificity to iron oxide compared to other sequences.
authors: Biomedical Translational Imaging Centre (BIOTIC), QEII Health Sciences Centre, 1796 Summer Street, Suite 3900, Halifax, NS, Canada. james.rioux@nshealth.ca.|Department of Radiology, Dalhousie University, Halifax, NS, Canada. james.rioux@nshealth.ca.|Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, Canada. james.rioux@nshealth.ca.
authors: James A
authors: JA
authors: Rioux
authors: Biomedical Translational Imaging Centre (BIOTIC), QEII Health Sciences Centre, 1796 Summer Street, Suite 3900, Halifax, NS, Canada.|Department of Radiology, Dalhousie University, Halifax, NS, Canada.|School of Health Sciences, Dalhousie University, Halifax, NS, Canada.|Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, Canada.|Department of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada.
authors: Steven D
authors: SD
authors: Beyea
authors: Biomedical Translational Imaging Centre (BIOTIC), QEII Health Sciences Centre, 1796 Summer Street, Suite 3900, Halifax, NS, Canada.|Department of Radiology, Dalhousie University, Halifax, NS, Canada.|Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, Canada.|Department of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada.
authors: Chris V
authors: CV
authors: Bowen
mesh_terms: D000465:Algorithms; D000818:Animals; D016477:Artifacts; D044962:Data Compression; D006801:Humans; D007089:Image Enhancement; D007090:Image Interpretation, Computer-Assisted; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D051379:Mice; D008810:Mice, Inbred C57BL; D057054:Molecular Imaging; D019047:Phantoms, Imaging; D051381:Rats; D020318:Rats, Long-Evans; D012189:Retrospective Studies
keywords: Image reconstruction; Magnetic resonance imaging; Three-dimensional imaging