From the Department of Radiology, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan (M.L.K., S.I., U.M.); Department of Diagnostic Radiology and Neuroradiology, University Medicine Greifswald, Greifswald, Germany (M.L.K.); Neurospin, Bât 145, CEA-Saclay Center, Gif-sur-Yvette, France (D.L.B.); and Department of Radiology, Kyoto University Graduate School of Medicine, Kyoto, Japan (D.L.B.).
Radiology. 2020 Apr;295(1):127-135. doi: 10.1148/radiol.2020191498. Epub 2020 Feb 11.
Background Diffusion-weighted (DW) MRI-based elastography has recently been proposed for noninvasive liver fibrosis staging but requires evaluation in a larger number of patients. Purpose To compare DW MRI and MR elastography for the assessment of liver fibrosis. Materials and Methods In this retrospective study, patients underwent MR elastography and DW MRI between November 2017 and April 2018. Shear modulus measured by MR elastography (μ) was obtained in each patient from regions of interest placed on liver stiffness maps by two independent readers. Shifted apparent diffusion coefficient (ADC) was calculated from DW MRI ( = 200 and 1500 sec/mm) and converted to DW MRI-based virtual shear modulus (μ). MRI-based liver fibrosis stages were estimated from μ and μ values (F0-F4) and serum fibrosis markers were assessed. Statistical analyses included Bland-Altman plots, Bayesian prediction, and receiver operating characteristic analyses. Results Seventy-four patients (mean age, 68 years ± 9 [standard deviation]; 45 men) were evaluated. Interreader coefficient of reproducibility was 0.86 kPa for DW MRI and 1.2 kPa for MR elastography. Strong correlation between shifted ADC and μ was observed ( = 0.81; < .001), showing high agreement between μ and μ values (mean difference, -0.02 kPa ± 0.88; < .001). DW MRI-based fibrosis staging agreed with MR elastography-based staging in 55% of patients (41 of 74) and within one stage difference in 35% of patients (26 of 74). Binarization into insignificant (F0-F1) and significant fibrosis (F2-F4) showed agreement in 85% of patients (63 of 74; κ = 0.85). Compared with serum markers (area under the receiver operating characteristic curve [AUC], 0.50-0.69), μ showed better performance in discriminating fibrosis stages F0-F2 from F3-F4 (AUC, 0.79; 95% confidence interval: 0.69, 0.90), whereas serum markers showed slightly better results for F0-F1 versus F2-F4 differentiation (fibrosis stages were estimated by using MR elastography). Combining DW MRI with serum markers provided a trend toward highest discriminative performance (AUC, μ + aspartate aminotransferase-to-platelet radio index: F0-F1 vs F2-F4, 0.81 [95% confidence interval: 0.69, 0.93], = .17; F0-F2 vs F3-F4, 0.83 [95% confidence interval: 0.74, 0.92], = .07; and AUC μ + Fibrosis 4 score: F0-F1 vs F2-F4, 0.78 [95% confidence interval: 0.64, 0.92], < .30; F0-F2 vs F3-F4, 0.81 [95% confidence interval: 0.71, 0.91], = .08). Conclusion MR elastography and diffusion-weighted (DW) MRI-based estimation of liver fibrosis stage showed high agreement. DW MRI shows potential as an alternative to MR elastography for noninvasive fibrosis staging without the need for mechanical vibration setup. © RSNA, 2020
背景 基于弥散加权（DW）MRI 的弹性成像是最近提出的用于非侵入性肝纤维化分期的方法，但需要在更多的患者中进行评估。目的 比较 DW MRI 和 MR 弹性成像在评估肝纤维化方面的应用。材料与方法 本回顾性研究纳入 2017 年 11 月至 2018 年 4 月间接受 MR 弹性成像和 DW MRI 检查的患者。两位独立的读者在肝脏硬度图上放置感兴趣区，测量 MR 弹性成像得出的剪切模量（μ）。从 DW MRI （ = 200 和 1500 sec/mm）中计算出移位表观扩散系数（ADC），并将其转换为 DW MRI 虚拟剪切模量（μ）。根据 μ 和 μ 值（F0-F4）评估 MRI 肝纤维化分期，并评估血清纤维化标志物。统计分析包括 Bland-Altman 图、贝叶斯预测和受试者工作特征曲线分析。结果 74 例患者（平均年龄，68 岁 ± 9 [标准差]；45 例男性）纳入研究。DW MRI 的两位观察者间重复性系数为 0.86 kPa，MR 弹性成像为 1.2 kPa。观察到移位 ADC 与 μ 之间具有很强的相关性（ = 0.81； <.001），表明 μ 值与 μ 值之间具有高度一致性（平均差值，-0.02 kPa ± 0.88； <.001）。DW MRI 肝纤维化分期与 MR 弹性成像分期在 55%（74 例中的 41 例）的患者中一致，在 35%（74 例中的 26 例）的患者中相差一个分期。将纤维化分为无意义（F0-F1）和显著纤维化（F2-F4）在 85%（74 例中的 63 例）的患者中具有一致性（κ = 0.85）。与血清标志物（受试者工作特征曲线下面积 [AUC]，0.50-0.69）相比，μ 在区分纤维化 F0-F2 期与 F3-F4 期时具有更好的性能（AUC，0.79；95%置信区间：0.69，0.90），而血清标志物在区分 F0-F1 期与 F2-F4 期时具有稍好的结果（纤维化分期由 MR 弹性成像评估）。DW MRI 与血清标志物联合使用可提供最高的鉴别性能（AUC，μ+天冬氨酸氨基转移酶/血小板比值指数：F0-F1 与 F2-F4 比较，0.81 [95%置信区间：0.69，0.93]， =.17；F0-F2 与 F3-F4 比较，0.83 [95%置信区间：0.74，0.92]， =.07；AUC，μ+Fibrosis 4 评分：F0-F1 与 F2-F4 比较，0.78 [95%置信区间：0.64，0.92]， <.30；F0-F2 与 F3-F4 比较，0.81 [95%置信区间：0.71，0.91]， =.08）。结论 MR 弹性成像和基于 DW MRI 的肝纤维化分期具有高度一致性。DW MRI 作为一种替代 MR 弹性成像的方法，具有在无需机械振动设置的情况下进行非侵入性纤维化分期的潜力。
