title: Wave-CAIPI for highly accelerated MP-RAGE imaging.
abstract: OBJECTIVE
  To introduce a highly accelerated T1-weighted magnetization-prepared rapid gradient echo (MP-RAGE) acquisition that uses wave-controlled aliasing in parallel imaging (wave-CAIPI) encoding to retain high image quality.
  
  
  METHODS
  Significant acceleration of the MP-RAGE sequence is demonstrated using the wave-CAIPI technique. Here, sinusoidal waveforms are used to spread aliasing in all three directions to improve the g-factor. Combined with a rapid (2 s) coil sensitivity acquisition and data-driven trajectory calibration, we propose an online integrated acquisition-reconstruction pipeline for highly efficient MP-RAGE imaging.
  
  
  RESULTS
  The 9-fold accelerated MP-RAGE acquisition can be performed in 71 s, with a maximum and average g-factor of gmax= 1.27 and gavg= 1.06 at 3T. Compared with the state-of-the-art method controlled aliasing in parallel imaging results in higher acceleration (2D-CAIPIRINHA), this is a factor of 4.6/1.4 improvement in gmax/gavg. In addition, we demonstrate a 57 s acquisition at 7T with 12-fold acceleration. This acquisition has a g-factor performance of gmax= 1.15 and gavg= 1.04.
  
  
  CONCLUSIONS
  Wave encoding overcomes the g-factor noise amplification penalty and allows for an order of magnitude acceleration of MP-RAGE acquisitions. Magn Reson Med 79:401-406, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA.|Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Polak
authors.affiliation: Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA.|Harvard Medical School, Boston, Massachusetts, USA.|Harvard-MIT Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
authors.forename: Kawin
authors.initials: K
authors.lastname: Setsompop
authors.affiliation: Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA.|Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Stephen F
authors.initials: SF
authors.lastname: Cauley
authors.affiliation: Harvard Medical School, Boston, Massachusetts, USA.|Fetal-Neonatal Neuroimaging & Developmental Science Center, Boston Children's Hospital, Boston, Massachusetts, USA.
authors.forename: Borjan A
authors.initials: BA
authors.lastname: Gagoski
authors.affiliation: Siemens Medical Solutions Inc, Malvern, Pennsylvania, USA.
authors.forename: Himanshu
authors.initials: H
authors.lastname: Bhat
authors.affiliation: Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Maier
authors.affiliation: Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Bachert
authors.affiliation: Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA.|Harvard Medical School, Boston, Massachusetts, USA.|Harvard-MIT Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
authors.forename: Lawrence L
authors.initials: LL
authors.lastname: Wald
authors.affiliation: Department of Radiology, A. A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts, USA.|Harvard Medical School, Boston, Massachusetts, USA.
authors.forename: Berkin
authors.initials: B
authors.lastname: Bilgic
mesh_terms: D000465:Algorithms; D001921:Brain / Q000000981:diagnostic imaging*; D002138:Calibration; D005260:Female; D066128:Gray Matter / Q000000981:diagnostic imaging; D064368:Healthy Volunteers; D006801:Humans; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008280:Magnetics; D008297:Male; D012984:Software
keywords: CAIPIRINHA; ESPIRiT; MP-RAGE; fast imaging; wave-CAIPI