Intra-individual comparison of liver stiffness measurements by magnetic resonance elastography and two-dimensional shear-wave elastography in 888 patients

Intra-individual comparison of liver stiffness measurements by magnetic resonance elastography and two-dimensional shear-wave elastography in 888 patients Hideo Ichikawa1, Eisuke Yasuda1, Takashi Kumada2, Kenji Takeshima3, Sadanobu Ogawa3, Akikazu Tsunekawa3, Tatsuya Goto3, Koji Nakaya1, Tomoyuki Akita4, Junko Tanaka4 ※ Author affiliations appear at the end of this article. Purpose: Quantitative elastography methods, such as ultrasound two-dimensional shear-wave elastography (2D-SWE) and magnetic resonance elastography (MRE), are used to diagnose liver fibrosis. The present study compared liver stiffness determined by 2D-SWE and MRE within individuals and analyzed the degree of agreement between the two techniques. Methods: In total, 888 patients who underwent 2D-SWE and MRE were analyzed. Bland-Altman analysis was performed after both types of measurements were log-transformed to a normal distribution and converted to a common set of units using linear regression analysis for differing scales. The expected limit of agreement (LoA) was defined as the square root of the sum of the squares of 2D-SWE and MRE precision. The percentage difference was expressed as (2D-SWEMRE)/mean of the two methods×100. Results: A Bland-Altman plot showed that the bias and upper and lower LoAs (ULoA and LLoA) were 0.0002 (95% confidence interval [CI], -0.0057 to 0.0061), 0.1747 (95% CI, 0.1646 to 0.1847), and -0.1743 (95% CI, -0.1843 to -0.1642), respectively. In terms of percentage difference, the mean, ULoA, and LLoA were -0.5944%, 19.8950%, and -21.0838%, respectively. The calculated expected LoA was 17.1178% (95% CI, 16.6353% to 17.6002%), and 789 of 888 patients (88.9%) had a percentage difference within the expected LoA. The intraclass correlation coefficient of the two methods indicated an almost perfect correlation (0.8231; 95% CI, 0.8006 to 0.8432; P<0.001). Conclusion: Bland-Altman analysis demonstrated that 2D-SWE and MRE were interchangeable within a clinically acceptable range. Keywords: Two-dimensional shear-wave elastography; Magnetic resonance elastography; Bland-Altman analysis; Intraclass correlation coefficient; Proton density fat fraction Key points: Many studies have demonstrated that magnetic resonance elastography (MRE) has the same or significantly better diagnostic accuracy than two-dimensional shear-wave elastography (2D-SWE) for detecting fibrosis stages using liver biopsy as a reference. BlandAltman analysis of 2D-SWE and MRE showed that the mean, upper limit of agreement (LoA), and lower LoA expressed in terms of the percentage difference were -0.5944%, 19.8950%, and -21.0838%, respectively. The calculated expected LoA was 17.1178%, and 789 of 888 patients (88.9%) had a percentage difference within the expected LoA. Bland-Altman analysis demonstrated that 2D-SWE and MRE were interchangeable within a clinically acceptable range. e-ultrasonography.org Ultrasonography 42(1), January 2023 ORIGINAL ARTICLE https://doi.org/10.14366/usg.22052 eISSN: 2288-5943 Ultrasonography 2023;42:65-77 Received: March 28, 2022 Revised: June 20, 2022 Accepted: June 21, 2022 Correspondence to: Eisuke Yasuda, PhD, Department of Medical Imaging, Graduate School of Health Science, Suzuka University of Medical Science, Suzuka, Mie 5100293, Japan Tel. +81-059-383-8991 Fax. +81-059-383-9666 E-mail: This is an Open Access article distributed under the terms of the Creative Commons Attribution NonCommercial License (http://creativecommons.org/ licenses/by-nc/4.0/) which permits unrestricted noncommercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Copyright © 2023 Korean Society of Ultrasound in Medicine (KSUM) How to cite this article: Ichikawa H, Yasuda E, Kumada T, Takeshima K, Ogawa S, Tsunekawa A, et al. Intra-individual comparison of liver stiffness measurements by magnetic resonance elastography and twodimensional shear-wave elastography in 888 patients. Ultrasonography. 2023 Jan;42(1):6577. 65 Hideo Ichikawa, et al. Introduction Materials and Methods Hepatic fibrosis, a form of scarring that results from repeated liver injury, leads to the accumulation of extracellular matrix components in the liver parenchyma [1]. Fibrosis can progress to cirrhosis and is an important risk factor for hepatocellular carcinoma (HCC) and hepatic failure [2]. An accurate diagnosis of the degree of hepatic fibrosis is essential for patient management, including for predicting the prognosis and monitoring responses to fibrosis therapies. Liver biopsy is the gold standard for staging hepatic fibrosis. However, it is an invasive procedure and has several disadvantages, including patient reluctance, pain, and hemoperitoneum, and its complications may be life-threatening [3]. These disadvantages limit the role of biopsy for serial monitoring. Furthermore, liver biopsy assesses only about 1/50,000th of the whole liver volume and is thus prone to sampling error and intra- and inter-observer variation [4]. Magnetic resonance elastography (MRE) has emerged as a highly accurate, noninvasive imaging test to measure liver stiffness (LS) and thus quantify liver fibrosis [5]. However, using MRE to test a large number of patients at risk for liver fibrosis is costly and practically difficult. There are also complaints that the MRE examination space is small, the vibrations cause feelings of sickness, and the examination time is too long, all of which limit the feasibility of magnetic resonance imaging (MRI) examinations. Ultrasoundbased methods for LS quantification can also assess fibrosis and are quicker to perform. Of these techniques, transient elastography (TE) may be the most widely performed, and it has been extensively investigated [6,7]. Nonetheless, studies comparing MRE and TE have shown that MRE has superior performance [5,8,9]. Two-dimensional shear-wave elastography (2D-SWE) has been introduced as an additional approach for ultrasound-based LS measurement. Unlike TE, 2D-SWE offers real-time simultaneous B-mode visualization of the liver and incorporates flexible placement of larger regions of interest (ROIs), thereby potentially reducing technical failures and providing more robust assessment in challenging cases [10,11]. A relatively limited number of investigations have compared MRE and 2D-SWE [5,9,12], and they yielded heterogeneous results, had limited sample sizes, or did not focus on factors impacting the agreement of measurements obtained by both methods. The aim of this study was thus to perform an intra-individual comparison of LS measurements using MRE and 2D-SWE in a large patient sample, with attention to factors impacting agreement. 66 Compliance with Ethical Standards This retrospective study was approved by the Institutional Review Board (20200423-5) of Ogaki Municipal Hospital and was carried out in compliance with the Helsinki Declaration. The Institutional Review Board approved this study after the examinations were c (...truncated)