title: The effect of respiratory and cardiac motion in liver diffusion tensor imaging (DTI).
abstract: OBJECTIVE
  To evaluate the effect of respiratory and cardiac motion on diffusion tensor imaging (DTI) metrics in healthy human liver.
  
  
  METHODS
  Fifteen healthy subjects, participating in either part of this study, were scanned using a 1.5-T magnetic resonance imaging (MRI) device. Coronal liver DTI (6 diffusion-encoding directions; b, 300 mm/s) during breath holding was compared to free breathing. Cardiac motion effects were evaluated by comparing breath-held DTI scans acquired during both diastole and systole.
  
  
  RESULTS
  Free breathing resulted in a significantly increased mean diffusivity (P < 0.05), λ1 (P < 0.01), λ2 (P < 0.05), and λ3 (P < 0.01) compared to breath holding. During systole significant increases in fractional anisotropy (P < 0.05), mean diffusivity (P < 0.05), and λ1 (P < 0.05), compared to systole, were found in the left lobe. The right lobe, which is less affected by cardiac motion, showed no significant change in DTI metrics over the cardiac cycle.
  
  
  CONCLUSIONS
  Respiratory and cardiac motion tends to increase liver DTI metrics.
authors.affiliation: From the *Department of Medical Physics and Applied Radiation Science, McMaster University, Hamilton, Ontario, Canada, †Image Research Center, St. Joseph's Healthcare, Hamilton Ontario, Canada; ‡Medical Physics and Research Department, and §Department of Diagnostic and Interventional Radiology, Hong Kong Sanatorium and Hospital, Hong Kong Special Administrative Region, China; ∥School of Biomedical Engineering, McMaster University, Hamilton, Ontario, Canada; and ¶Department of Electrical and Computer Engineering, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Oi Lei
authors.initials: OL
authors.lastname: Wong
authors.forename: Gladys
authors.initials: G
authors.lastname: Gloh Lo
authors.forename: Raymond
authors.initials: R
authors.lastname: Lee
authors.forename: Wing
authors.initials: W
authors.lastname: Wa Li
authors.forename: Po
authors.initials: P
authors.lastname: Lung Chan
authors.forename: Siu
authors.initials: S
authors.lastname: Ki Yu
authors.forename: Michael D
authors.initials: MD
authors.lastname: Noseworthy
mesh_terms: D000328:Adult; D016477:Artifacts; D062485:Breath Holding; D056324:Diffusion Tensor Imaging / Q000379:methods*; D005260:Female; D006321:Heart / Q000033:anatomy & histology* / Q000502:physiology*; D006801:Humans; D008099:Liver / Q000033:anatomy & histology* / Q000502:physiology*; D008297:Male; D009038:Motion; D009068:Movement; D012016:Reference Values; D015203:Reproducibility of Results; D015656:Respiratory Mechanics / Q000502:physiology*; D012680:Sensitivity and Specificity