Department of Radiation Oncology, Graduate School of Medicine, Yamaguchi University 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8535, Japan.
Department of Radiological technology, Yamaguchi University Hospital 1-1-1 Minamikogushi, Ube, Yamaguchi 755-8535, Japan.
Phys Med Biol. 2022 Jul 19;67(15). doi: 10.1088/1361-6560/ac7d35.
. This study aimed to produce a three-dimensional liver elasticity map using the finite element method (FEM) and respiration-induced motion captured by T1-weighted magnetic resonance images (FEM-E-map) and to evaluate whether FEM-E-maps can be an imaging biomarker comparable to magnetic resonance elastography (MRE) for assessing the distribution and severity of liver fibrosis.. We enrolled 14 patients who underwent MRI and MRE. T1-weighted MR images were acquired during shallow inspiration and expiration breath-holding, and the displacement vector field (DVF) between two images was calculated using deformable image registration. FEM-E-maps were constructed using FEM and DVF. First, three Poisson's ratio settings (0.45, 0.49, and 0.499995) were validated and optimized to minimize the difference in liver elasticity between the FEM-E-map and MRE. Then, the whole and regional liver elasticity values estimated using FEM-E-maps were compared with those obtained from MRE using Pearson's correlation coefficients. Spearman rank correlations and chi-square histograms were used to compare the voxel-level elasticity distribution.. The optimal Poisson's ratio was 0.49. Whole liver elasticity estimated using FEM-E-maps was strongly correlated with that measured using MRE ( = 0.96). For regional liver elasticity, the correlation was 0.84 for the right lobe and 0.82 for the left lobe. Spearman analysis revealed a moderate correlation for the voxel-level elasticity distribution between FEM-E-maps and MRE (0.61 ± 0.10). The small chi-square distances between the two histograms (0.11 ± 0.07) indicated good agreement.. FEM-E-maps represent a potential imaging biomarker for visualizing the distribution of liver fibrosis using only T1-weighted images obtained with a common MR scanner, without any additional examination or special elastography equipment. However, additional studies including comparisons with biopsy findings are required to verify the reliability of this method for clinical application.
. 本研究旨在利用有限元法（FEM）和 T1 加权磁共振成像（FEM-E-map）捕获的呼吸运动生成三维肝脏弹性图，并评估 FEM-E-map 是否可以作为一种成像生物标志物，与磁共振弹性成像（MRE）相媲美，用于评估肝脏纤维化的分布和严重程度。.. 我们纳入了 14 名接受 MRI 和 MRE 检查的患者。在浅吸气和呼气屏气期间采集 T1 加权 MR 图像，并使用可变形图像配准计算两幅图像之间的位移矢量场（DVF）。使用 FEM 和 DVF 构建 FEM-E-map。首先，验证并优化了三种泊松比设置（0.45、0.49 和 0.499995），以最小化 FEM-E-map 和 MRE 之间的肝脏弹性差异。然后，使用 Pearson 相关系数比较 FEM-E-map 估计的整体和区域肝脏弹性值与 MRE 获得的弹性值。Spearman 秩相关和卡方直方图用于比较体素水平的弹性分布。.. 最佳泊松比为 0.49。FEM-E-map 估计的整个肝脏弹性与 MRE 测量值高度相关（r=0.96）。对于区域肝脏弹性，右叶和左叶的相关性分别为 0.84 和 0.82。Spearman 分析显示 FEM-E-map 和 MRE 之间体素水平弹性分布具有中等相关性（0.61±0.10）。两个直方图之间的小卡方距离（0.11±0.07）表明一致性良好。.. FEM-E-map 代表了一种潜在的成像生物标志物，可使用普通磁共振扫描仪获得的 T1 加权图像可视化肝脏纤维化的分布，无需任何额外的检查或特殊的弹性成像设备。然而，需要进一步的研究，包括与活检结果的比较，以验证该方法用于临床应用的可靠性。
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