title: Comparison of physiological triggering schemes for diffusion-weighted magnetic resonance imaging in kidneys.
abstract: OBJECTIVE
  To determine the potential benefit of combined respiratory-cardiac triggering for diffusion-weighted imaging (DWI) of kidneys compared to respiratory triggering alone (RT).
  
  
  METHODS
  Renal DWI was performed in 17 volunteers comparing RT, combined respiratory-cardiac triggering (RCT), and combined respiratory-cardiac triggering with slice position correction (RCTF). Data were analyzed in three ways: A1) Model-free analysis of the signal stability over repeated measurements; A2) Analysis of the deviation from diffusion-model fitting comparing the root mean squared error (RMSE), assessing within-subject variabilities; and A3) Analysis of diffusion indices comparing between-subject variabilities.
  
  
  RESULTS
  Combined respiratory-cardiac triggering yielded lower signal fluctuations and more reliable diffusion parameter estimation than respiratory triggering alone in all three analysis methods: A1) The mean coefficient of variation (CV) for all subjects was 4.2 +/- 1.1% and 4.3 +/- 0.9% for RCT and RCTF, respectively, which was significantly lower compared to RT (5.3 +/- 0.9%, P < 0.005); A2) RT yielded significantly higher RMSEs than RCT and RCTF; A3) The between-subject variations of diffusion indices tended toward higher values for RT. The results were independent of perfusion contributions to the DWI data. No difference was determined between RCT and RCTF. Total acquisition time was only slightly prolonged for respiratory-cardiac double-triggering.
  
  
  CONCLUSIONS
  Respiratory-cardiac double-triggering seems advantageous for renal DWI.
authors.affiliation: Department of Clinical Research, University of Bern, Bern, Switzerland.
authors.forename: Tobias
authors.initials: T
authors.lastname: Binser
authors.forename: Harriet C
authors.initials: HC
authors.lastname: Thoeny
authors.forename: Ute
authors.initials: U
authors.lastname: Eisenberger
authors.forename: Alto
authors.initials: A
authors.lastname: Stemmer
authors.forename: Chris
authors.initials: C
authors.lastname: Boesch
authors.forename: Peter
authors.initials: P
authors.lastname: Vermathen
mesh_terms: D000328:Adult; D000465:Algorithms; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007668:Kidney / Q000033:anatomy & histology*; D008297:Male; D015203:Reproducibility of Results; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods*; D012680:Sensitivity and Specificity