Department of Diagnostic Radiology, Dalhousie University, Halifax, Nova Scotia, B3H 2Y9, Canada.
Department of Pathology, Dalhousie University, Halifax, Nova Scotia, Canada.
J Magn Reson Imaging. 2022 Nov;56(5):1448-1456. doi: 10.1002/jmri.28154. Epub 2022 Mar 14.
Non-alcoholic fatty liver disease (NAFLD) is increasingly common worldwide and can lead to the development of cirrhosis, liver failure and cancer. Virtual magnetic resonance elastography (VMRE), which is based on a shifted apparent diffusion coefficient (sADC), is a potential noninvasive method to assess liver fibrosis without the specialized hardware and expertise required to implement traditional MR elastography (MRE). Although hepatic steatosis is known to confound ADC measurements, previous studies using VMRE have not corrected for hepatic fat fraction.
To compare VMRE, corrected for the confounding effects of unsuppressed fat signal, to MRE and biopsy in subjects with suspected NAFLD.
Prospective, cross-sectional.
A total of 49 adult subjects with suspected NAFLD (18 male; median age 55 years, range 33-74 years) who underwent liver biopsy.
FIELD STRENGTH/SEQUENCE: 3T, diffusion-weighted spin echo planar, chemical-shift encoded (IDEAL IQ) and MRE sequences.
Two observers drew regions of interest on sADC, proton density fat fraction and MRE-derived stiffness maps. Fat-corrected sADC values were used to calculate the diffusion-based shear modulus according to the VMRE method. Predicted fibrosis stage for MRE and VMRE was determined using previously published cut-off values.
The relationship between VMRE and MRE was assessed with least-squares linear regression (coefficient of determination, R ). Agreement between MRE and VMRE-predicted fibrosis stage was evaluated with a kappa coefficient and accuracy compared using McNemar's test. A one-way ANOVA determined if the fat-corrected sADC (VMRE) and MRE differed by fibrosis stage. A P value < 0.05 was considered statistically significant.
Least squares regression of VMRE vs. MRE revealed R = 0.046 and a slope that was not significantly different from zero (P = 0.14). There was no agreement between MRE and VMRE-predicted fibrosis stage (kappa = -0.01). The proportion of correctly predicted fibrosis stage was significantly higher for MRE compared to VMRE. MRE was significantly associated with fibrosis stage, but fat-corrected sADC was not (P = 0.24).
Fat-corrected VMRE was not associated with fibrosis stage in NAFLD. Further investigation is required if VMRE is to be considered in subjects with NAFLD.
1 TECHNICAL EFFICACY: Stage 2.
非酒精性脂肪性肝病（NAFLD）在全球范围内越来越常见，可导致肝硬化、肝功能衰竭和肝癌的发生。基于表观弥散系数偏移（sADC）的虚拟磁共振弹性成像（VMRE）是一种潜在的无创性方法，可在不使用传统磁共振弹性成像（MRE）所需的特殊硬件和专业知识的情况下评估肝纤维化。尽管肝脂肪变性已知会干扰 ADC 测量，但以前使用 VMRE 的研究并未校正肝脂肪分数。
比较 VMRE（校正未抑制脂肪信号的混杂影响）与 MRE 和活检在疑似 NAFLD 患者中的表现。
前瞻性、横断面研究。
共 49 名疑似 NAFLD 的成年受试者（18 名男性；中位年龄 55 岁，范围 33-74 岁），均接受了肝活检。
磁场强度/序列：3T，扩散加权自旋回波平面，化学位移编码（IDEAL IQ）和 MRE 序列。
两名观察者在 sADC、质子密度脂肪分数和 MRE 衍生的硬度图上绘制感兴趣区。使用基于 VMRE 方法的脂肪校正 sADC 值来计算基于扩散的剪切模量。使用先前发表的截断值确定 MRE 和 VMRE 预测的纤维化阶段。
采用最小二乘线性回归（决定系数，R ）评估 VMRE 与 MRE 的关系。采用 kappa 系数评估 MRE 和 VMRE 预测的纤维化阶段之间的一致性，并使用 McNemar 检验比较准确性。单因素方差分析确定脂肪校正 sADC（VMRE）和 MRE 是否因纤维化阶段而异。P 值<0.05 被认为具有统计学意义。
VMRE 与 MRE 的最小二乘回归显示 R 为 0.046，斜率与零无显著差异（P=0.14）。MRE 和 VMRE 预测的纤维化阶段之间无一致性（kappa=-0.01）。与 VMRE 相比，MRE 预测纤维化阶段的正确率明显更高。MRE 与纤维化阶段显著相关，但脂肪校正 sADC 无相关性（P=0.24）。
在 NAFLD 中，脂肪校正后的 VMRE 与纤维化阶段无关。如果要在 NAFLD 患者中考虑 VMRE，则需要进一步研究。
1 技术功效：2 级。
