title: Non-invasive determination of hepatic steatosis by acoustic structure quantification from ultrasound echo amplitude.
abstract: OBJECTIVE
  To use leptin-deficient (ob/ob) mice with demonstrated differences in steatosis levels to test a new diagnostic method using the acoustical structure quantification (ASQ) mode and the associated analytical parameter, "focal disturbance ratio" (FD-ratio).
  
  
  METHODS
  Nine ob/ob mice, at 5, 8, and 12 wk of age (n = 3 in each age group), were used as models for hepatic steatosis. Echo signals obtained from ultrasonography in the mice were analyzed by ASQ, which uses a statistical analysis of echo amplitude to estimate inhomogeneity in the diagnostic region. FD-ratio, as calculated from this analysis, was the focus of the present study. FD-ratio and fat droplet areas and sizes were compared between age groups.
  
  
  RESULTS
  No fibrosis or inflammation was observed in any of the groups. The fat droplet area significantly (P < 0.01) increased with age from 1.25% ± 0.28% at 5 wk to 31.07% ± 0.48% at 8 wk to 51.69% ± 3.19% at 12 wk. The median fat droplet size also significantly (P < 0.01) increased with age, from 1.33 (0.55-10.52) μm at 5 wk, 2.82 (0.61-44.13) μm at 8 wk and 6.34 (0.66-81.83) μm at 12 wk. The mean FD-ratio was 0.42 ± 0.11 at 5 wk, 0.11 ± 0.05 at 8 wk, and 0.03 ± 0.02 at 12 wk. The FD-ratio was significantly lower at 12 wk than at 5 wk and 8 wk (P < 0.01). A significant negative correlation was observed between the FD-ratio and either the fat droplet area (r = -0.7211, P = 0.0017) or fat droplet size (r = -0.9811, P = 0.0052).
  
  
  CONCLUSIONS
  This tool for statistical analysis of signals from ultrasonography using the FD-ratio can be used to accurately quantify fat in vivo in an animal model of hepatic steatosis, and may serve as a quantitative biomarker of hepatic steatosis.
authors.affiliation: Division of Gastroenterology and Hepatology, Department of Internal Medicine, Iwate Medical University, Iwate, Japan. hikuro@iwate-med.ac.jp
authors.forename: Hidekatsu
authors.initials: H
authors.lastname: Kuroda
authors.forename: Keisuke
authors.initials: K
authors.lastname: Kakisaka
authors.forename: Naohisa
authors.initials: N
authors.lastname: Kamiyama
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Oikawa
authors.forename: Mio
authors.initials: M
authors.lastname: Onodera
authors.forename: Kei
authors.initials: K
authors.lastname: Sawara
authors.forename: Kanta
authors.initials: K
authors.lastname: Oikawa
authors.forename: Ryujin
authors.initials: R
authors.lastname: Endo
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Takikawa
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Suzuki
mesh_terms: D000162:Acoustics; D000367:Age Factors; D000818:Animals; D004195:Disease Models, Animal; D005234:Fatty Liver / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology; D050356:Lipid Metabolism; D008099:Liver / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D008820:Mice, Obese; D065626:Non-alcoholic Fatty Liver Disease; D014463:Ultrasonography