Department of Diagnostic Physics, Oslo University Hospital, Oslo, Norway.
Department of Physics, University of Oslo, Oslo, Norway.
J Magn Reson Imaging. 2021 May;53(5):1510-1521. doi: 10.1002/jmri.27475. Epub 2021 Jan 5.
Changes in brain stiffness can be an important biomarker for neurological disease. Magnetic resonance elastography (MRE) quantifies tissue stiffness, but the results vary between acquisition and reconstruction methods.
To measure MRE repeatability and estimate the effect of different reconstruction methods and varying data quality on estimated brain stiffness.
Prospective.
Fifteen healthy subjects.
FIELD STRENGTH/SEQUENCE: 3T MRI, gradient-echo elastography sequence with a 50 Hz vibration frequency.
Imaging was performed twice in each subject. Images were reconstructed using a curl-based and a finite-element-model (FEM)-based method. Stiffness was measured in the whole brain, in white matter, and in four cortical and four deep gray matter regions. Repeatability coefficients (RC), intraclass correlation coefficients (ICC), and coefficients of variation (CV) were calculated. MRE data quality was quantified by the ratio between shear waves and compressional waves.
Median values with range are presented. Reconstruction methods were compared using paired Wilcoxon signed-rank tests, and Spearman's rank correlation was calculated between MRE data quality and stiffness. Holm-Bonferroni corrections were employed to adjust for multiple comparisons.
In the whole brain, CV was 4.3% and 3.8% for the curl and the FEM reconstruction, respectively, with 4.0-12.8% for subregions. Whole-brain ICC was 0.60-0.74, ranging from 0.20 to 0.89 in different regions. RC for the whole brain was 0.14 kPa and 0.17 kPa for the curl and FEM methods, respectively. FEM reconstruction resulted in 39% higher stiffness than the curl reconstruction (P < 0.05). MRE data quality, defined as shear-compression wave ratio, was higher in peripheral regions than in central regions of the brain (P < 0.05). No significant correlations were observed between MRE data quality and stiffness estimates.
MRE of the human brain is a robust technique in terms of repeatability. Caution is warranted when comparing stiffness values obtained with different techniques.
1 TECHNICAL EFFICACY STAGE: 1.
大脑硬度的变化可能是神经疾病的一个重要生物标志物。磁共振弹性成像（MRE）定量组织硬度，但在采集和重建方法之间结果有所不同。
测量 MRE 的可重复性，并估计不同的重建方法和不同的数据质量对估计脑硬度的影响。
前瞻性。
15 名健康受试者。
磁场强度/序列：3T MRI，具有 50Hz 振动频率的梯度回波弹性成像序列。
对每位受试者进行两次成像。使用基于 curl 和基于有限元模型（FEM）的方法对图像进行重建。在整个大脑、白质以及四个皮质和四个深部灰质区域测量硬度。计算重复性系数（RC）、组内相关系数（ICC）和变异系数（CV）。通过剪切波与压缩波的比值来量化 MRE 数据质量。
呈现中位数和范围。使用配对 Wilcoxon 符号秩检验比较重建方法，并用 Spearman 秩相关分析 MRE 数据质量与硬度之间的关系。采用 Holm-Bonferroni 校正法进行多重比较校正。
在整个大脑中，基于 curl 和 FEM 重建的 CV 分别为 4.3%和 3.8%，亚区的 CV 为 4.0%-12.8%。整个大脑的 ICC 为 0.60-0.74，不同区域的 ICC 范围为 0.20-0.89。整个大脑的 RC 分别为基于 curl 和 FEM 方法的 0.14kPa 和 0.17kPa。FEM 重建的硬度比 curl 重建高 39%（P<0.05）。MRE 数据质量（定义为剪切-压缩波比）在大脑的外周区域高于中央区域（P<0.05）。未观察到 MRE 数据质量与硬度估计值之间存在显著相关性。
MRE 对人脑是一种可靠的技术，具有可重复性。在比较不同技术获得的硬度值时应谨慎。
1 技术功效等级：1。
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