title: Quantification of choline concentration following liver cell apoptosis using 1H magnetic resonance spectroscopy.
abstract: OBJECTIVE
  To evaluate the feasibility of quantifying liver choline concentrations in both normal and apoptotic rabbit livers in vivo, using 1H magnetic resonance spectroscopy (1H-MRS).
  
  
  METHODS
  1H-MRS was performed in 18 rabbits using a 1.5T GE MR system with an eight-channel head/neck receiving coil. Fifteen rabbits were injected with sodium selenite at a dose of 10 μmol/kg to induce the liver cell apoptosis. Point-resolved spectroscopy sequence-localized spectra were obtained from 10 livers once before and once 24 h after sodium selenite injection in vivo. T1 and T2 relaxation time of water and choline was measured separately in the livers of three healthy rabbits and three selenite-treated rabbits. Hematoxylin and eosin and dUTP-biotin nick end labeling (TUNEL) staining was used to detect and confirm apoptosis. Choline peak areas were measured relative to unsuppressed water using LCModel. Relaxation attenuation was corrected using the average of T1 and T2 relaxation time. The choline concentration was quantified using a formula, which was tested by a phantom with a known concentration.
  
  
  RESULTS
  Apoptosis of hepatic cells was confirmed by TUNEL assay. In phantom experiment, the choline concentration (3.01 mmol/L), measured by 1H-MRS, was in good agreement with the actual concentration (3 mmol/L). The average T1 and T2 relaxation time of choline was 612 ± 15 ms and 74 ± 4 ms in the control group and 670 ± 27 ms and 78 ± 5 ms in apoptotic livers in vivo, respectively. Choline was quantified in 10 rabbits, once before and once after the injection with sodium selenite. The choline concentration decreased from 14.5 ± 7.57 mmol/L before sodium selenite injection to 10.8 ± 6.58 mmol/L (mean ± SD, n = 10) after treatment (Z = -2.395, P < 0.05, two-sample paired Wilcoxon test).
  
  
  CONCLUSIONS
  1H-MRS can be used to quantify liver choline in vivo using unsuppressed water as an internal reference. Decreased liver choline concentrations are found in sodium selenite-treated rabbits undergoing liver cell apoptosis.
authors.affiliation: Department of Medical Imaging, The Second Affiliated Hospital, Shantou University Medical College, Shantou 515041, Guangdong Province, China.
authors.forename: Zhi-Wei
authors.initials: ZW
authors.lastname: Shen
authors.forename: Zhen
authors.initials: Z
authors.lastname: Cao
authors.forename: Ke-Zeng
authors.initials: KZ
authors.lastname: You
authors.forename: Zhong-Xian
authors.initials: ZX
authors.lastname: Yang
authors.forename: Ye-Yu
authors.initials: YY
authors.lastname: Xiao
authors.forename: Xiao-Fang
authors.initials: XF
authors.lastname: Cheng
authors.forename: Yao-Wen
authors.initials: YW
authors.lastname: Chen
authors.forename: Ren-Hua
authors.initials: RH
authors.lastname: Wu
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002794:Choline / Q000032:analysis*; D022781:Hepatocytes / Q000187:drug effects / Q000473:pathology*; D008099:Liver / Q000737:chemistry / Q000166:cytology / Q000473:pathology; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011817:Rabbits; D018038:Sodium Selenite / Q000494:pharmacology
chemical_list: D018038:Sodium Selenite; D002794:Choline