title: Unenhanced fat fraction ratios obtained by MR and enhanced T2* values with liver-specific MR contrast agents for diagnosis of non-alcoholic steatohepatitis in rats.
abstract: BACKGROUND
  Non-invasive MR imaging is expected to be used for accurate diagnosis and quantification of non-alcoholic steatohepatitis (NASH), because NASH is a progressive fatty liver disease. New MR techniques, such as fat fraction ratio (FFR) and T2* value measurement, have attracted an increasing attention, because those techniques can measure quantitative parameters of fibrosis, fat and iron deposition in the liver.
  
  
  OBJECTIVE
  To investigate the potential of FFR and T2* value in NASH with pre-enhancement, gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) or super-paramagnetic iron oxide (SPIO)-enhanced MRI.
  
  
  METHODS
  Twenty-eight rats were divided equally into four groups (one control group and three NASH groups). All rats underwent unenhanced, Gd-EOB-DTPA, and SPIO-enhanced MRI. The T2* value of the liver was measured for each image sequence, and then changes in T2* values before and after each injection were analyzed using Dunnett's test. The reduction rate of T2* value before and 13 min after injection of Gd-EOB-DTPA or SPIO was analyzed using Mann-Whitney's U test. Moreover, FFR of the liver was measured before enhancement, and the relationship between fat fraction and the calculated fat area percentage on a pathological specimen was examined using Spearman's correlation test.
  
  
  RESULTS
  On pre-enhancement, FFR and T2* value were 26.0% ± 12.0% and 21.5 ± 4.2 ms for all NASH groups, and 0.9% ± 0.5% and 30.8 ±-5.5 ms for control, respectively. Both FFR and T2* values were significantly different between the NASH and control groups. The reduction rate of T2* value was significantly lower in the NASH groups than in the control group on SPIO-enhanced MRI, though there was no significant difference on Gd-EOB-DTPA-enhanced MRI. FFR was correlated with the calculated fat area percentage for the pathological specimen.
  
  
  CONCLUSIONS
  Pre-enhancement FFR, T2* value measurement and reduction rate of T2* value on SPIO-enhanced MRI may help estimate the progress of liver fat deposition and fibrosis in NASH.
authors.affiliation: Department of Radiology, Kinki University Faculty of Medicine, Osaka, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Okada
authors.forename: Takashi
authors.initials: T
authors.lastname: Katsube
authors.forename: Seishi
authors.initials: S
authors.lastname: Kumano
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kagawa
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Araki
authors.forename: Natsuko
authors.initials: N
authors.lastname: Tsuda
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Okuaki
authors.forename: Izumi
authors.initials: I
authors.lastname: Imaoka
authors.forename: Noboru
authors.initials: N
authors.lastname: Tanigawa
authors.forename: Kazunari
authors.initials: K
authors.lastname: Ishii
authors.forename: Takamichi
authors.initials: T
authors.lastname: Murakami
mesh_terms: D000818:Animals; D003287:Contrast Media; D003911:Dextrans; D004195:Disease Models, Animal; D005234:Fatty Liver / Q000175:diagnosis*; D019786:Gadolinium DTPA; D007089:Image Enhancement / Q000379:methods; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D008297:Male; D065626:Non-alcoholic Fatty Liver Disease; D051381:Rats; D017207:Rats, Sprague-Dawley; D018709:Statistics, Nonparametric
chemical_list: D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; C073590:gadolinium ethoxybenzyl DTPA; C065507:ferumoxides; D019786:Gadolinium DTPA