Estimation of four-dimensional CT-based imaging biomarker of liver fibrosis using finite element method
Estimation of four-dimensional CT-based imaging biomarker of liver fibrosis using finite element method
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使用有限元法估计基于四维CT的肝纤维化成像生物标志物
DOI：
10.1117/12.2548280
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Yuasa Yuki
中科院分区：
文献类型：
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作者：
Fujimoto Koya;Shiinoki Takehiro;Yuasa Yuki
本研究基于放疗计划获取的四维计算机断层扫描（4DCT）图像，开发了基于有限元法（FEM）的肝脏弹性估计方法，并评估了估计弹性作为诊断肝纤维化的生物标志物的可行性。本研究纳入了15例接受4DCT成像和gadoxate -acid （Gd-EOB-DTPA）增强磁共振成像（MRI）的患者。利用可变形图像配准（实际呼吸诱导位移）计算吸气末和呼气末4DCT图像之间的位移向量场。在此基础上，采用模拟呼吸诱导位移法（FEM）模拟呼吸过程中的位移。肝脏模型各单元的弹性均经过优化，最大限度地减少了实际与模拟呼吸引起的位移之间的误差。gd - eob - dtpaa增强MRI，采用全肝、全脾平均信号强度计算肝脾信号强度比（LSR）。评估弹性和LSR与两种血清生物标志物（APRI：天冬氨酸转氨酶血小板比率指数，FIB-4：纤维化-4指数）的相关性。弹性与apri评分（r= 0.82）和fib -4评分（r= 0.86）有较强的相关性。另一方面，LSR与aprii评分（r= 0.32）和fib -4评分（r= 0.30）呈正相关。肝脏模型中实际与模拟呼吸性位移误差的平均值±标准差为0.63±0.41 mm。在本研究中，肝弹性是利用有限元和呼吸引起的肝脏运动从4DCT图像估计。此外，估计的弹性可以作为诊断不同程度肝纤维化的可行成像生物标志物。
This study developed the estimation method of the liver elasticity using the finite element method (FEM) based on the four-dimensional computed tomography (4DCT) images acquired for radiotherapy planning, and to evaluate the feasibility of estimated elasticity as a biomarker for diagnose liver fibrosis. Fifteen patients who underwent 4DCT images and gadoxetate-acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) were enrolled in this study. The displacement vector fields were calculated between 4DCT images at the end-inspiration and at the end-exhalation using deformable image registration (actual respiratory-induced displacement). Further, we simulated the displacement during respiration by using the FEM (simulated respiratory-induced displacement). The elasticity in each element of liver model was optimized minimalizing the error between actual and simulated respiratory-induced displacement. In Gd-EOB-DTPAenhanced MRI, liver-to-spleen signal intensity ratio (LSR) was calculated using the mean signal intensity for whole liver and spleen. The correlations with two serum biomarkers (APRI: aspartate-aminotransferase to platelet ratio index, FIB-4: Fibrosis-4 index) for elasticity and for LSR were evaluated. The elasticity were strong correlation with APRI-score (r= 0.82), and with FIB-4-score (r= 0.86). On the other hand, LSR were modelate correlation with APRI-score (r= 0.32), and with FIB-4-score (r= 0.30). The mean ± standard deviation of errors between actual and simulated respiratory-induced displacement in the liver model was 0.63 ± 0.41 mm. In this study, liver elasticity was estimated using the FEM and respiratory-induced liver motion obtained from 4DCT images. Furthermore, the estimated elasticity could be a feasible imaging biomarker for diagnose the various degrees of liver fibrosis.