title: Q-space truncation and sampling in diffusion spectrum imaging.
abstract: To characterize the q-space truncation and sampling on the spin-displacement probability density function (PDF) in diffusion spectrum imaging (DSI).
  
  
  
  DSI data were acquired using the MGH-USC connectome scanner (Gmax= 300 mT/m) with bmax= 30,000 s/mm2, 17 × 17 × 17, 15 × 15 × 15 and 11 × 11 × 11 grids in ex vivo human brains and bmax= 10,000 s/mm2, 11 × 11 × 11 grid in vivo. An additional in vivo scan using bmax=7,000 s/mm2, 11 × 11 × 11 grid was performed with a derated gradient strength of 40 mT/m. PDFs and orientation distribution functions (ODFs) were reconstructed with different q-space filtering and PDF integration lengths, and from down-sampled data by factors of two and three.
  
  
  
  Both ex vivo and in vivo data showed Gibbs ringing in PDFs, which becomes the main source of artifact in the subsequently reconstructed ODFs. For down-sampled data, PDFs interfere with the first replicas or their ringing, leading to obscured orientations in ODFs.
  
  
  
  The minimum required q-space sampling density corresponds to a field-of-view approximately equal to twice the mean displacement distance (MDD) of the tissue. The 11 × 11 × 11 grid is suitable for both ex vivo and in vivo DSI experiments. To minimize the effects of Gibbs ringing, ODFs should be reconstructed from unfiltered q-space data with the integration length over the PDF constrained to around the MDD. Magn Reson Med 76:1750-1763, 2016. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Department of Electrical Engineering, Stanford University, Stanford, California, USA.|Department of Radiology, Stanford University, Richard M. Lucas Center for Imaging, Stanford, California, USA.
authors.forename: Qiyuan
authors.initials: Q
authors.lastname: Tian
authors.affiliation: Department of Psychology, Stanford University, Stanford, California, USA.
authors.forename: Ariel
authors.initials: A
authors.lastname: Rokem
authors.affiliation: Department of Pathology, Brigham and Women's Hospital, Boston, Massachusetts, USA.
authors.forename: Rebecca D
authors.initials: RD
authors.lastname: Folkerth
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Boston, MA, USA.
authors.forename: Aapo
authors.initials: A
authors.lastname: Nummenmaa
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Boston, MA, USA.
authors.forename: Qiuyun
authors.initials: Q
authors.lastname: Fan
authors.affiliation: Department of Radiology, Massachusetts General Hospital, Athinoula A. Martinos Center for Biomedical Imaging, Boston, MA, USA.|Department of Neurology, Massachusetts General Hospital, Boston, Massachusetts, USA.
authors.forename: Brian L
authors.initials: BL
authors.lastname: Edlow
authors.affiliation: Department of Radiology, Stanford University, Richard M. Lucas Center for Imaging, Stanford, California, USA.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: McNab
mesh_terms: D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology*; D003198:Computer Simulation; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008297:Male; D015233:Models, Statistical; D015203:Reproducibility of Results; D018401:Sample Size; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult
keywords: Gibbs ringing artifacts; aliasing artifacts; diffusion spectrum imaging; ex vivo imaging; high b-value; q-space truncation and sampling