Hepatic fat quantification using the two-point Dixon method and fat color maps based on non-alcoholic fatty liver disease activity score

Tatsuya Hayashi; Satoshi Saitoh; Junji Takahashi; Yoshinori Tsuji; Kenji Ikeda; Masahiro Kobayashi; Yusuke Kawamura; Takeshi Fujii; Masafumi Inoue; Tosiaki Miyati; Hiromitsu Kumada

doi:10.1111/hepr.12767

Hepatic fat quantification using the two-point Dixon method and fat color maps based on non-alcoholic fatty liver disease activity score

Hepatol Res. 2017 Apr;47(5):455-464. doi: 10.1111/hepr.12767. Epub 2016 Jul 31.

Authors

Tatsuya Hayashi^{1

2

3

4}, Satoshi Saitoh^{2

5

6}, Junji Takahashi^{1

2}, Yoshinori Tsuji^{1

2}, Kenji Ikeda^{2

5}, Masahiro Kobayashi^{2

5}, Yusuke Kawamura^{2

5}, Takeshi Fujii^{2

7}, Masafumi Inoue⁸, Tosiaki Miyati³, Hiromitsu Kumada^{2

5}

Affiliations

¹ Department of Radiological Technology, Toranomon Hospital, Tokyo, Japan.
² Okinaka Memorial Institute for Medical Research, Tokyo, Japan.
³ Faculty of Health Sciences, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa, Ishikawa, Japan.
⁴ Department of Medical Radiology, Faculty of Medical Technology, Teikyo University, Tokyo, Japan.
⁵ Department of Hepatology, Toranomon Hospital, Tokyo, Japan.
⁶ Department of Radiology, Toranomon Hospital, Tokyo, Japan.
⁷ Department of Pathology, Toranomon Hospital, Tokyo, Japan.
⁸ Department of Ophthalmology, Japan Community Health Care Organization Tokyo Shinjuku Medical Center, Tokyo, Japan.

PMID: 27351583
DOI: 10.1111/hepr.12767

Abstract

Aim: The two-point Dixon method for magnetic resonance imaging (MRI) is commonly used to non-invasively measure fat deposition in the liver. The aim of the present study was to assess the usefulness of MRI-fat fraction (MRI-FF) using the two-point Dixon method based on the non-alcoholic fatty liver disease activity score.

Methods: This retrospective study included 106 patients who underwent liver MRI and MR spectroscopy, and 201 patients who underwent liver MRI and histological assessment. The relationship between MRI-FF and MR spectroscopy-fat fraction was used to estimate the corrected MRI-FF for hepatic multi-peaks of fat. Then, a color FF map was generated with the corrected MRI-FF based on the non-alcoholic fatty liver disease activity score. We defined FF variability as the standard deviation of FF in regions of interest. Uniformity of hepatic fat was visually graded on a three-point scale using both gray-scale and color FF maps. Confounding effects of histology (iron, inflammation and fibrosis) on corrected MRI-FF were assessed by multiple linear regression.

Results: The linear correlations between MRI-FF and MR spectroscopy-fat fraction, and between corrected MRI-FF and histological steatosis were strong (R² = 0.90 and R² = 0.88, respectively). Liver fat variability significantly increased with visual fat uniformity grade using both of the maps (ρ = 0.67-0.69, both P < 0.001). Hepatic iron, inflammation and fibrosis had no significant confounding effects on the corrected MRI-FF (all P > 0.05).

Conclusions: The two-point Dixon method and the gray-scale or color FF maps based on the non-alcoholic fatty liver disease activity score were useful for fat quantification in the liver of patients without severe iron deposition.

Keywords: fatty liver; magnetic resonance imaging; non-alcoholic fatty liver disease; non-alcoholic steatohepatitis.