Retrospective Study
Copyright ©The Author(s) 2018. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jul 21, 2018; 24(27): 3013-3020
Published online Jul 21, 2018. doi: 10.3748/wjg.v24.i27.3013
Liver intravoxel incoherent motion diffusion-weighted imaging for the assessment of hepatic steatosis and fibrosis in children
Hyun Joo Shin, Haesung Yoon, Myung-Joon Kim, Seok Joo Han, Hong Koh, Seung Kim, Mi-Jung Lee
Hyun Joo Shin, Haesung Yoon, Myung-Joon Kim, Mi-Jung Lee, Department of Radiology, Severance Hospital, Severance Pediatric Liver Disease Research Group, Research Institute of Radiological Science, Yonsei University College of Medicine, Seoul 03722, South Korea
Seok Joo Han, Department of Surgery, Severance Hospital, Severance Pediatric Liver Disease Research Group, Yonsei University College of Medicine, Seoul 03722, South Korea
Hong Koh, Seung Kim, Division of Gastroenterology, Hepatology and Nutrition, Department of Pediatrics, Severance Children’s Hospital, Severance Pediatric Liver Disease Research Group, Yonsei University College of Medicine, Seoul 03722, South Korea
Author contributions: Shin HJ and Lee MJ designed the research; Shin J, Yoon H, and Lee MJ performed the research and wrote the manuscript; Shin HJ, Yoon H and Lee MJ analyzed the data; Kim MJ, Han SJ, Koh H, and Kim S contributed analytic tools; Kim MJ, Shin HJ, Yoon H, Han SJ, Koh H, Kim S, and Lee MJ revised and approved the final version.
Institutional review board statement: This study was reviewed and approved by the local ethics committee of the Severance Hospital, Yonsei University (register no. 1-2017-0014).
Informed consent statement: Because of the retrospective and anonymous character of this study, the need for informed consent was waived by the institutional review board.
Conflict-of-interest statement: All authors declare no conflicts-of-interest related to this article.
Data sharing statement: No additional data are available.
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/
Correspondence to: Mi-Jung Lee, MD, PhD, Assistant Professor, Department of Radiology, Severance Hospital, Severance Pediatric Liver Disease Research Group, Research Institute of Radiological Science, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul 03722, South Korea. mjl1213@yuhs.ac
Telephone: +82-2-22287400 Fax: +82-2-3933035
Received: March 16, 2018
Peer-review started: March 17, 2018
First decision: April 24, 2018
Revised: April 26, 2018
Accepted: June 9, 2018
Article in press: June 9, 2018
Published online: July 21, 2018
Processing time: 124 Days and 16.2 Hours
ARTICLE HIGHLIGHTS
Research background

Liver disease including steatosis and fibrosis is not uncommon in pediatric population. Quantitative and non-invasive examination of liver status is important in children because biopsy has a limited role from its sampling error and invasiveness.

Research motivation

Intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) is an advanced diffusion-weighted imaging (DWI) technique. It can separate the perfusion and diffusion components from the conventional apparent diffusion coefficient (ADC) in the liver. Previous studies demonstrated IVIM values were more useful than ADC value for the evaluation of liver disease in adults, using the pure molecular diffusion (D), pseudo-diffusion (D*), and perfusion fracture (f) parameters. However, limited studies have assessed hepatic steatosis and fibrosis in children using IVIM. In addition, no study has focused on pediatric livers with enough b-values for IVIM.

Research objectives

The purpose of the study was to evaluate the usefulness of IVIM DWI technique with multiple b-values for evaluating hepatic steatosis and fibrosis in children and to know the correlation between IVIM parameters and the degree of hepatic steatosis and fibrosis measured with MRI in children.

Research methods

We retrospectively reviewed liver IVIM MRI of children (≤ 18 years) who performed MRI with 8 b-values under the suspicion of liver steatosis or fibrosis from 2013 to 2016. In addition to the conventional ADC value, perfusion related parameters (D*, f) and diffusion related parameter (D) were measured in the liver. Degree of hepatic steatosis was measured using MR proton density fat fracture (PDFF) and degree of hepatic fibrosis was measured using MR elastography (MRE). Perfusion and diffusion parameters were compared between normal, fatty liver, and fibrotic liver groups. Effects of hepatic steatosis and fibrosis on IVIM parameters were assessed.

Research results

Hepatic steatosis and fibrosis affected IVIM parameters differently in children. Perfusion related parameters (D*, f) were significantly lower in the fibrosis group compared with other groups. MR PDFF demonstrated a positive correlation with the f, representing blood volume. MRE value was negatively correlated with the D*, representing endovascular blood flow velocity. However, D and ADC value were not affected.

Research conclusions

Liver IVIM MRI with multiple b-values was useful for evaluating hepatic steatosis and fibrosis in children. Hepatic steatosis and fibrosis influenced perfusion and diffusion parameters differently. As increasing hepatic steatosis, blood volume was significantly increased. As increasing hepatic fibrosis, endovascular blood flow velocity was significantly decreased. However, true molecular diffusion and conventional ADC were not affected. Therefore, IVIM MRI can be a useful tool for evaluating hepatic steatosis and fibrosis in children.

Research perspectives

Perfusion related parameters from IVIM MRI can be used for the evaluation of hepatic steatosis and fibrosis in children. Further study is needed to determine whether the IVIM parameters are affected by different histopathologies and etiologies of pediatric hepatic steatosis and fibrosis.