title: Comparison and reproducibility of ADC measurements in breathhold, respiratory triggered, and free-breathing diffusion-weighted MR imaging of the liver.
abstract: OBJECTIVE
  To compare and determine the reproducibility of apparent diffusion coefficient (ADC) measurements of the normal liver parenchyma in breathhold, respiratory triggered, and free-breathing diffusion-weighted magnetic resonance imaging (DWI).
  
  
  METHODS
  Eleven healthy volunteers underwent three series of DWI. Each DWI series consisted of one breathhold, one respiratory triggered, and two free-breathing (thick and thin slice acquisition) scans of the liver, at b-values of 0 and 500 s/mm2. ADCs of the liver parenchyma were compared by using nonparametric tests. Reproducibility was assessed by the Bland-Altman method.
  
  
  RESULTS
  Mean ADCs (in 10(-3) mm2/sec) in respiratory triggered DWI (2.07-2.27) were significantly higher than mean ADCs in breathhold DWI (1.57-1.62), thick slice free-breathing DWI (1.62-1.65), and thin slice free-breathing DWI (1.57-1.66) (P<0.005). Ranges of mean difference in ADC measurement+/-limits of agreement between two scans were -0.02-0.05+/-0.16-0.24 in breathhold DWI, -0.14-0.20+/-0.59-0.60 in respiratory triggered DWI, -0.03-0.03+/-0.20-0.29 in thick slice free-breathing DWI, and -0.01-0.09+/-0.21-0.29 in thin slice free-breathing DWI.
  
  
  CONCLUSIONS
  ADC measurements of the normal liver parenchyma in respiratory triggered DWI are significantly higher and less reproducible than in breathhold and free-breathing DWI.
authors.affiliation: Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands. thomaskwee@gmail.com
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Kwee
authors.forename: Taro
authors.initials: T
authors.lastname: Takahara
authors.forename: Dow-Mu
authors.initials: DM
authors.lastname: Koh
authors.forename: Rutger A J
authors.initials: RA
authors.lastname: Nievelstein
authors.forename: Peter R
authors.initials: PR
authors.lastname: Luijten
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D016477:Artifacts; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008099:Liver / Q000033:anatomy & histology*; D008297:Male; D015203:Reproducibility of Results; D015656:Respiratory Mechanics; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods*; D012680:Sensitivity and Specificity; D055815:Young Adult