title: Proton and sodium MRI assessment of fluid level in calf tissue.
abstract: OBJECTIVE
  To investigate the feasibility of using (1)H and (23)Na MRI to detect fluid levels in the lower leg muscle.
  
  
  METHODS
  Proton and sodium MRI was applied to detect body fluid levels in the lower leg muscles of 18 healthy young male subjects at 3T and 4T. The paradigms under investigation were a postural change from sitting upright to lying supine, and saline infusion.
  
  
  RESULTS
  We found that the average proton MR signal in gastrocnemius and soleus muscles were reduced following the postural change by 3.5% +/- 1.4% (P < 0.05) and rose following saline infusion by 3.7% +/- 0.9% (P < 0.01). More dramatically, the sodium MR signal decreased by 7.1% +/- 1.2% (P < 0.01) following the postural change and increased following saline infusion by 12% +/- 3.8% (P < 0.05). The ratio of intra- to extracellular fluid levels was 1.6 +/- 0.5 for the subjects based on the acquired proton and sodium data.
  
  
  CONCLUSIONS
  Our results indicate that proton and sodium MRI can be used to assess fluid levels in the lower extremities, and this technique may be applied to evaluate fluid retention.
authors.affiliation: Brain Imaging Center, McLean Hospital, Harvard Medical School, Belmont, Massachusetts, USA. chun@mclean.harvard.edu
authors.forename: Chun S
authors.initials: CS
authors.lastname: Zuo
authors.forename: Rosemond A
authors.initials: RA
authors.lastname: Villafuerte
authors.forename: Michael E
authors.initials: ME
authors.lastname: Henry
authors.forename: Michelle
authors.initials: M
authors.lastname: Butman
authors.forename: Robert L
authors.initials: RL
authors.lastname: Dobbins
authors.forename: Yiwu
authors.initials: Y
authors.lastname: He
authors.forename: Barbara S
authors.initials: BS
authors.lastname: Orban
authors.forename: Kenroy
authors.initials: K
authors.lastname: Cayetano
authors.forename: Liqun
authors.initials: L
authors.lastname: Wang
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Brown
authors.forename: Derek J
authors.initials: DJ
authors.lastname: Nunez
authors.forename: John
authors.initials: J
authors.lastname: Brown
authors.forename: Perry F
authors.initials: PF
authors.lastname: Renshaw
mesh_terms: D000293:Adolescent; D000328:Adult; D001826:Body Fluids; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D018482:Muscle, Skeletal / Q000473:pathology*; D009132:Muscles / Q000378:metabolism*; D011522:Protons; D012964:Sodium / Q000494:pharmacology*
chemical_list: D011522:Protons; D012964:Sodium