title: Measurement of liver T₁ and T₂ relaxation times in an experimental mouse model of liver fibrosis.
abstract: OBJECTIVE
  To characterize changes in relaxation times of liver using quantitative magnetic resonance imaging (MRI) in an experimental mouse model of liver fibrosis. Quantitative MRI is a potentially robust method to characterize liver fibrosis. However, correlation between relaxation times and fibrosis stage has been controversial.
  
  
  METHODS
  Liver fibrosis was induced in male adult C57BL/6N mice (22-25 g; n = 12) by repetitive dosing of carbon tetrachloride (CCl(4) ). The animals were examined with a series of spin-echo (SE) images with varying TRs and multiecho SE imaging sequence at 7 T before and 2, 4, 6, and 8 weeks after CCl(4) insult. Hepatic T(1) and T(2) values were measured. Histology was performed with hematoxylin-eosin staining and Masson's trichrome staining.
  
  
  RESULTS
  Significant increase (P < 0.001) in hepatic T(1) was found at 2, 4, 6, and 8 weeks following CCl(4) insult as compared with that before insult. Meanwhile, hepatic T(2) at 2, 4, 6, and 8 weeks after CCl(4) insult was significantly higher (P < 0.001) than that before the insult. Liver histology showed collagen deposition, edema, and infiltration of inflammatory cells in livers with CCl(4) insult.
  
  
  CONCLUSIONS
  Both longitudinal and transverse relaxation times may serve as robust markers for liver fibrosis. With the advent of single breath-hold sequences for MR relaxometry, quantitative mapping of relaxation times can be routinely and reliably performed in abdominal organs and hence may be valuable and robust in detecting liver fibrosis at early phase and monitoring its progression.
authors.affiliation: Laboratory of Biomedical Imaging and Signal Processing, University of Hong Kong, Pokfulam, Hong Kong SAR, China.
authors.forename: April M
authors.initials: AM
authors.lastname: Chow
authors.forename: Darwin S
authors.initials: DS
authors.lastname: Gao
authors.forename: Shu Juan
authors.initials: SJ
authors.lastname: Fan
authors.forename: Zhongwei
authors.initials: Z
authors.lastname: Qiao
authors.forename: Frank Y
authors.initials: FY
authors.lastname: Lee
authors.forename: Jian
authors.initials: J
authors.lastname: Yang
authors.forename: Kwan
authors.initials: K
authors.lastname: Man
authors.forename: Ed X
authors.initials: EX
authors.lastname: Wu
mesh_terms: D000465:Algorithms; D000818:Animals; D004195:Disease Models, Animal; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008103:Liver Cirrhosis / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity