title: Metabolic imaging of human kidney triglyceride content: reproducibility of proton magnetic resonance spectroscopy.
abstract: OBJECTIVE
  To assess the feasibility of renal proton magnetic resonance spectroscopy for quantification of triglyceride content and to compare spectral quality and reproducibility without and with respiratory motion compensation in vivo.
  
  
  METHODS
  The Institutional Review Board of our institution approved the study protocol, and written informed consent was obtained. After technical optimization, a total of 20 healthy volunteers underwent renal proton magnetic resonance spectroscopy of the renal cortex both without and with respiratory motion compensation and volume tracking. After the first session the subjects were repositioned and the protocol was repeated to assess reproducibility. Spectral quality (linewidth of the water signal) and triglyceride content were quantified. Bland-Altman analyses and a test by Pitman were performed.
  
  
  RESULTS
  Linewidth changed from 11.5±0.4 Hz to 10.7±0.4 Hz (all data pooled, p<0.05), without and with respiratory motion compensation respectively. Mean % triglyceride content in the first and second session without respiratory motion compensation were respectively 0.58±0.12% and 0.51±0.14% (P = NS). Mean % triglyceride content in the first and second session with respiratory motion compensation were respectively 0.44±0.10% and 0.43±0.10% (P = NS between sessions and P = NS compared to measurements with respiratory motion compensation). Bland-Altman analyses showed narrower limits of agreement and a significant difference in the correlated variances (correlation of -0.59, P<0.05).
  
  
  CONCLUSIONS
  Metabolic imaging of the human kidney using renal proton magnetic resonance spectroscopy is a feasible tool to assess cortical triglyceride content in humans in vivo and the use of respiratory motion compensation significantly improves spectral quality and reproducibility. Therefore, respiratory motion compensation seems a necessity for metabolic imaging of renal triglyceride content in vivo.
authors.affiliation: Department of Radiology, Leiden University Medical Center (Leiden University), Leiden, The Netherlands. S.Hammer@lumc.nl
authors.forename: Sebastiaan
authors.initials: S
authors.lastname: Hammer
authors.forename: Aiko P J
authors.initials: AP
authors.lastname: de Vries
authors.forename: Paul
authors.initials: P
authors.lastname: de Heer
authors.forename: Maurice B
authors.initials: MB
authors.lastname: Bizino
authors.forename: Ron
authors.initials: R
authors.lastname: Wolterbeek
authors.forename: Ton J
authors.initials: TJ
authors.lastname: Rabelink
authors.forename: Joost
authors.initials: J
authors.lastname: Doornbos
authors.forename: Hildo J
authors.initials: HJ
authors.lastname: Lamb
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007668:Kidney / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D011522:Protons; D015203:Reproducibility of Results; D014280:Triglycerides / Q000378:metabolism*; D055815:Young Adult
chemical_list: D011522:Protons; D014280:Triglycerides