title: T1rho MR imaging is sensitive to evaluate liver fibrosis: an experimental study in a rat biliary duct ligation model.
abstract: OBJECTIVE
  To correlate spin-lattice relaxation time in the rotating frame (T1ρ) measurements with degree of liver fibrosis in a rat model.
  
  
  METHODS
  The protocols and procedures were approved by the local Animal Experimentation Ethics Committee. Liver fibrosis was induced with biliary duct ligation (BDL). Two studies, 1 month apart, were performed with a 3-T clinical imager. The first study involved longitudinal magnetic resonance (MR) imaging follow-up of BDL rats (n = 8) and control rats (n = 4) on days 8, 15, 21, and 29 after BDL. The second study involved MR imaging of another group of BDL and control rats (n = 5 for each) on days 24 and 38 after BDL. Hematoxylin-eosin and picrosirius red staining were performed in liver specimens from days 8, 15, 24, and 38 after BDL. Repeated-measures analysis of variance was used, and treatment groups were compared (Bonferroni adjustment).
  
  
  RESULTS
  On day 8, there were proliferation of bile duct and inflammatory cell infiltration around portal triads. While there was overlap, BDL rats (n = 8) demonstrated higher mean liver T1ρ values than did control rats (n = 4) on day 8 (46.7 msec ± 2.9 [standard deviation] vs 44.7 msec ± 1.2, P = .4). On day 15, BDL rats demonstrated liver fibrosis with a background of inflammatory infiltration. On day 15, mean T1ρ values in BDL rats could be largely separated from those in control rats (52.6 msec ± 6.0 vs 43.8 msec ± 1.5, P = .02). On day 24, BDL rats had liver T1ρ values 23.5% higher than in control rats (n = 5 for each group, P = .0007). Histomorphometric analysis showed that collagen content increased after surgery from days 8 to 24 (n = 6 for each group, P < .0001), with no further increase between days 24 and 38 (n = 6 for each group, P >.99).
  
  
  CONCLUSIONS
  In this model, liver fibrosis was detected with T1ρ MR imaging; the degree of fibrosis was correlated with degree of increase in T1ρ measurements.
  
  
  BACKGROUND
  http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11101638/-/DC1.
authors: Department of Imaging and Interventional Radiology, Prince of Wales Hospital, the Chinese University of Hong Kong, Shatin, Hong Kong SAR, China. yixiang_wang@cuhk.edu.hk
authors: Yi-Xiang J
authors: YX
authors: Wang
authors: Jing
authors: J
authors: Yuan
authors: Eagle S H
authors: ES
authors: Chu
authors: Minnie Y Y
authors: MY
authors: Go
authors: Hua
authors: H
authors: Huang
authors: Anil T
authors: AT
authors: Ahuja
authors: Joseph J Y
authors: JJ
authors: Sung
authors: Jun
authors: J
authors: Yu
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001652:Bile Ducts / Q000601:surgery; D004195:Disease Models, Animal; D008026:Ligation; D016014:Linear Models; D008103:Liver Cirrhosis / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051381:Rats; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index