title: Validation of MRI biomarkers of hepatic steatosis in the presence of iron overload in the ob/ob mouse.
abstract: OBJECTIVE
  To validate the utility and performance of a T 2 correction method for hepatic fat quantification in an animal model of both steatosis and iron overload.
  
  
  METHODS
  Mice with low (n = 6), medium (n = 6), and high (n = 8) levels of steatosis were sedated and imaged using a chemical shift-based fat-water separation method to obtain magnetic resonance imaging (MRI) fat-fraction measurements. Imaging was performed before and after each of two superparamagnetic iron oxide (SPIO) injections to create hepatic iron overload. Fat-fraction maps were reconstructed with and without T 2 correction. Fat-fraction with and without T 2 correction and T 2 measurements were compared after each injection. Liver tissue was harvested and imaging results were compared to triglyceride extraction and histology grading.
  
  
  RESULTS
  Excellent correlation was seen between MRI fat-fraction and tissue-based fat quantification. Injections of SPIOs led to increases in R 2 (=1/T 2). Measured fat-fraction was unaffected by the presence of iron when T 2 correction was used, whereas measured fat-fraction dramatically increased without T 2 correction.
  
  
  CONCLUSIONS
  Hepatic fat-fraction measured using a T 2-corrected chemical shift-based fat-water separation method was validated in an animal model of steatosis and iron overload. T 2 correction enables robust fat-fraction estimation in both the presence and absence of iron, and is necessary for accurate hepatic fat quantification.
authors: Department of Radiology, University of Wisconsin, Madison, Wisconsin, USA.
authors: Catherine D G
authors: CD
authors: Hines
authors: Rashmi
authors: R
authors: Agni
authors: Calista
authors: C
authors: Roen
authors: Ian
authors: I
authors: Rowland
authors: Diego
authors: D
authors: Hernando
authors: Eric
authors: E
authors: Bultman
authors: Debra
authors: D
authors: Horng
authors: Huanzhou
authors: H
authors: Yu
authors: Ann
authors: A
authors: Shimakawa
authors: Jean H
authors: JH
authors: Brittain
authors: Scott B
authors: SB
authors: Reeder
mesh_terms: D050154:Adiposity; D000818:Animals; D016477:Artifacts; D015415:Biomarkers; D004195:Disease Models, Animal; D005234:Fatty Liver / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D019190:Iron Overload / Q000150:complications / Q000378:metabolism / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009929:Organ Size; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014280:Triglycerides / Q000032:analysis
chemical_list: D015415:Biomarkers; D014280:Triglycerides