title: Influence of calcium on choline measurements by 1H MR spectroscopy of thigh muscles.
abstract: OBJECTIVE
  To study the effects of calcium on the choline peak measurements with 1H MR spectroscopy.
  
  
  METHODS
  The thigh muscles of two cadaveric specimens were prospectively evaluated on a 3 T MR unit before and after the injection of calcium carbonate (up to 0.4322 g). The choline peaks of 147 spectra from 10 different anatomic locations were quantitatively evaluated. The influence of the calcium concentration and its disposition with respect to the main magnetic field were considered. B0 phase maps were used to evaluate field inhomogeneities.
  
  
  RESULTS
  The presence of calcium led to a 43 % underestimation of the choline peak and the choline concentration (p = 0.0002 and 0.0036). The mean choline concentrations before and after CaCO3 injection were 3.53 ± 1.72 mmol/l and 1.58 ± 0.63 mmol/l. The influence of calcium carbonate on the choline peak estimations was proportional to the calcium concentration. There was a significant position-dependent difference in the estimation of the choline peak amplitude (p < 0.0154). Calcium injection led to a measurable increase in field inhomogeneities.
  
  
  CONCLUSIONS
  There was a significant underestimation of the choline peak amplitude and concentration in the presence of calcium, which might cause misinterpretations of MR spectra.
  
  
  CONCLUSIONS
  The presence of calcium led to significant underestimation of choline measurements. The influence of calcium is dependent on its concentration and distribution. Quantitative MR spectroscopy of calcified tumours should be interpreted with caution.
authors.affiliation: Service D'imagerie Guilloz, Hôpital Central, CHU Nancy, Nancy, 54000, France, ped_gt@hotmail.com.
authors.forename: Pedro A Gondim
authors.initials: PA
authors.lastname: Teixeira
authors.forename: Gabriela
authors.initials: G
authors.lastname: Hossu
authors.forename: François
authors.initials: F
authors.lastname: Kauffmann
authors.forename: Anou
authors.initials: A
authors.lastname: Sewonu
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Constans
authors.forename: Alain
authors.initials: A
authors.lastname: Blum
authors.forename: Jacques
authors.initials: J
authors.lastname: Felblinger
mesh_terms: D000369:Aged, 80 and over; D002102:Cadaver; D002119:Calcium Carbonate / Q000494:pharmacology*; D002794:Choline / Q000032:analysis*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D060526:Magnetic Fields; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008956:Models, Chemical; D018482:Muscle, Skeletal / Q000737:chemistry* / Q000187:drug effects*; D010767:Phosphorylcholine / Q000032:analysis; D011522:Protons; D013848:Thigh
chemical_list: D011522:Protons; D010767:Phosphorylcholine; D002119:Calcium Carbonate; D002794:Choline