Brief Article
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World J Gastroenterol. Aug 7, 2012; 18(29): 3889-3895
Published online Aug 7, 2012. doi: 10.3748/wjg.v18.i29.3889
Non-invasive determination of hepatic steatosis by acoustic structure quantification from ultrasound echo amplitude
Hidekatsu Kuroda, Keisuke Kakisaka, Naohisa Kamiyama, Takayoshi Oikawa, Mio Onodera, Kei Sawara, Kanta Oikawa, Ryujin Endo, Yasuhiro Takikawa, Kazuyuki Suzuki
Hidekatsu Kuroda, Keisuke Kakisaka, Takayoshi Oikawa, Mio Onodera, Kei Sawara, Kanta Oikawa, Ryujin Endo, Yasuhiro Takikawa, Kazuyuki Suzuki, Division of Gastroenterology and Hepatology, Department of Internal Medicine, Iwate Medical University, Iwate 020-8505, Japan
Naohisa Kamiyama, Ultrasound Systems Division, Toshiba Medical Systems Corporation, Tochigi 324-8550, Japan
Author contributions: Kuroda H and Kakisaka K contributed equally to this work; Kuroda H, Kakisaka K, Kamiyama N, Oikawa T, Onodera M, Sawara K, Oikawa K, Endo R, Takikawa Y and Suzuki K designed the research; Kuroda H and Kakisaka K performed the research and analyzed the data; Kuroda H wrote the paper.
Correspondence to: Hidekatsu Kuroda, MD, PhD, Division of Gastroenterology and Hepatology, Department of Internal Medicine, Iwate Medical University, Uchimaru 19-1, Morioka, Iwate 020-8505, Japan. hikuro@iwate-med.ac.jp
Telephone: +81-19-6515111 Fax: +81-19-6526664
Received: August 11, 2011
Revised: April 17, 2012
Accepted: May 6, 2012
Published online: August 7, 2012
Abstract

AIM: 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).

CONCLUSION: 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.

Keywords: Non-alcoholic fatty liver disease; Quantitation of hepatic steatosis; Animal model; Focal disturbance ratio; Acoustic structure quantification; Ultrasonography