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©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
Rational arrangement of measuring shear wave speed in the liver
Takeshi Yokoo, Tsutomu Kanefuji, Takeshi Suda, Itsuo Nagayama, Takahiro Hoshi, Satoshi Abe, Shinichi Morita, Hiroteru Kamimura, Kenya Kamimura, Atsunori Tsuchiya, Masaaki Takamura, Kazuyoshi Yagi, Shuji Terai
Takeshi Yokoo, Department of Preemptive Medicine for Digestive Diseases and Healthy Active Life, Niigata University School of Medicine, Niigata, Niigata 951-8122, Japan
Tsutomu Kanefuji, Division of Gastroenterology and Hepatology, Niigata Tokamachi Hospital, Tokamachi, Niigata 948-0065, Japan
Takeshi Suda, Itsuo Nagayama, Takahiro Hoshi, Satoshi Abe, Shinichi Morita, Kazuyoshi Yagi, Department of Gastroenterology and Hepatology, Uonuma Institute of Community Medicine, Niigata University Medical and Dental Hospital, Minami Uonuma, Niigata 949-7302, Japan
Hiroteru Kamimura, Kenya Kamimura, Atsunori Tsuchiya, Masaaki Takamura, Shuji Terai, Division of Gastroenterology and Hepatology, Graduate School of Medical and Dental Sciences, Niigata University, Niigata 951-8122, Japan
Author contributions: Each author is a main contributor to the following points; Yokoo T contributed to statistical analysis, and manuscript writing; Yokoo T and Kanefuji T critically revised the manuscript for important intellectual content; Suda T contributed to study concept, study design, analysis and interpretation of data, and manuscript writing; Nagayama I, Hoshi T, Abe S, Morita S, Kamimura H, Kamimura K, Tsuchiya A and Takamura M acquired the data; Yagi K supervised the study; Terai S contributed to administrative supervision.
Institutional review board statement: The review board of Niigata University Medical and Dental Hospital (Niigata) reviewed and approved the present study.
Informed consent statement: The review board of Niigata University Medical and Dental Hospital did not require informed consent for this study, because it was a retrospective study using medical records or noninvasive imaging examinations.
Conflict-of-interest statement: All authors have nothing to disclose in relation with this manuscript.
Data sharing statement: No additional data are available.
STROBE statement: The guidelines of the STROBE Statement have been adopted.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Takeshi Suda, MD, PhD, Professor, Department of Gastroenterology and Hepatology, Institute of Community Medicine, Niigata University Medical and Dental Hospital, 4132 Urasa, Minami Uonuma, Niigata 949-7302, Japan. tspitt@med.niigata-u.ac.jp
Telephone: +81-25-7773200 Fax: +81-25-7772811
Received: October 2, 2018
Peer-review started: October 10, 2018
First decision: November 8, 2018
Revised: November 18, 2018
Accepted: December 27, 2018
Article in press: December 28, 2018
Published online: May 28, 2019
BACKGROUND
Shear wave speed has been widely applied to quantify a degree of liver fibrosis. However, there is no standardized procedure, which makes it difficult to utilize the speed universally.
AIM
To provide procedural standardization of shear wave speed measurement.
METHODS
Point shear wave elastography (pSWE) was measured in 781 patients, and two-dimensional shear wave elastography (2dSWE) was measured on the same day in 18 cases. Regions-of-interest were placed at 12 sites, and the median and robust coefficient-of-variation (CVR) were calculated. A residual sum-of-square (Σdi2) was computed for bootstrap values of 1000 iterations in 18 cases with each assumption of 1 to 12 measurements. The proportion of the Σdi2 (%Σdi2) was calculated as the ratio of Σdi2 to pSWE after converting it based on the correlation between pSWE and 2dSWE.
RESULTS
The CVR showed a significantly broader distribution in the left lobe (P < 0.0001), and the smallest CVR in the right anterior segment that covered 95% cases was 40.4%. pSWE was significantly higher in the left lobe than in the right lobe (1.63 ± 0.78 m/s vs 1.61 ± 0.78 m/s, P = 0.0004), and the difference between the lobes became further discrete when the subjects were limited to the cases with a CVR less than 40.4% in any segment (1.76 ± 0.80 m/s vs 1.70 ± 0.82 m/s, P < 0.0001). The highest values of the CVR in every 0.1 m/s interval were plotted in convex upward along pSWE and peaked at 1.93 m/s. pSWE and 2dSWE were significantly correlated (P < 0.0001, r = 0.95). In 216000 resamples from 18 cases, the %Σdi2 of 12 sites was 8.0% and gradually increased as the acquisition sites decreased to reach a significant difference with a %Σdi2 of 7 sites (P = 0.027).
CONCLUSION
These data suggest that shear wave speed should be measured at 8 or more sites of spreading in both lobes.
Core tip: Liver stiffness measurements play a key role in the management of chronic liver diseases; however, a standard procedure of liver stiffness measurements has not been established yet. This study provides the information for standardization of a measuring site and number of liver stiffness measurements from the statistical point of view.
