title: Optimization of Scan Parameters to Reduce Acquisition Time for Diffusion Kurtosis Imaging at 1.5T.
abstract: OBJECTIVE
  To shorten acquisition of diffusion kurtosis imaging (DKI) in 1.5-tesla magnetic resonance (MR) imaging, we investigated the effects of the number of b-values, diffusion direction, and number of signal averages (NSA) on the accuracy of DKI metrics.
  
  
  METHODS
  We obtained 2 image datasets with 30 gradient directions, 6 b-values up to 2500 s/mm(2), and 2 signal averages from 5 healthy volunteers and generated DKI metrics, i.e., mean, axial, and radial kurtosis (MK, K∥, and K⊥) maps, from various combinations of the datasets. These maps were estimated by using the intraclass correlation coefficient (ICC) with those from the full datasets.
  
  
  RESULTS
  The MK and K⊥ maps generated from the datasets including only the b-value of 2500 s/mm(2) showed excellent agreement (ICC, 0.96 to 0.99). Under the same acquisition time and diffusion directions, agreement was better of MK, K∥, and K⊥ maps obtained with 3 b-values (0, 1000, and 2500 s/mm(2)) and 4 signal averages than maps obtained with any other combination of numbers of b-value and varied NSA. Good agreement (ICC > 0.6) required at least 20 diffusion directions in all the metrics.
  
  
  CONCLUSIONS
  MK and K⊥ maps with ICC greater than 0.95 can be obtained at 1.5T within 10 min (b-value = 0, 1000, and 2500 s/mm(2); 20 diffusion directions; 4 signal averages; slice thickness, 6 mm with no interslice gap; number of slices, 12).
authors.affiliation: Central Research Laboratory, Hitachi, Ltd.
authors.forename: Suguru
authors.initials: S
authors.lastname: Yokosawa
authors.forename: Makoto
authors.initials: M
authors.lastname: Sasaki
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Bito
authors.forename: Kenji
authors.initials: K
authors.lastname: Ito
authors.forename: Fumio
authors.initials: F
authors.lastname: Yamashita
authors.forename: Jonathan
authors.initials: J
authors.lastname: Goodwin
authors.forename: Satomi
authors.initials: S
authors.lastname: Higuchi
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Kudo
mesh_terms: D000328:Adult; D000465:Algorithms; D001921:Brain / Q000033:anatomy & histology; D066264:Datasets as Topic; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods / Q000706:statistics & numerical data*; D017352:Echo-Planar Imaging / Q000379:methods / Q000706:statistics & numerical data; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted / Q000379:methods / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged