用深度学习实现实时脑部磁共振弹性成像反演,精度媲美传统方法。
Real-time nonlinear inversion of magnetic resonance elastography with operator learning
- 用算子学习框架oNLI,输入位移场的旋度,直接预测弹性图。
- 整体误差仅8.4%(μ')和10.0%(μ''),比CNN低近一半。
- 3万倍提速,适合临床实时应用,尤其关注空间细节的研究者。
目的:开发并评估一种用于脑部磁共振弹性成像(MRE)非线性反演(NLI)的算子学习框架,实现与传统NLI相当空间精度的实时反演。方法:本回顾性研究使用61名受试者(平均年龄37.4岁;34名为女性)的3D MRE数据训练框架。采用10折交叉验证,以测量位移场的复数旋度为输入,以NLI生成的参考弹性图为输出,训练预测型深度算子学习框架(oNLI)。引入结构先验机制,类似文献中的软先验正则化,提升空间精度。评估指标包括不同脑区大小下的皮尔逊相关系数、绝对相对误差和结构相似性指数。统计分析采用配对t检验,比较oNLI变体与卷积神经网络基线模型。结果:oNLI在全脑的绝对百分比误差为μ':8.4 ± 0.5,μ'':10.0 ± 0.7;而CNN为μ':15.8 ± 0.8,μ'':26.1 ± 1.1。oNLI在全脑及所有子区域的存储模量和损耗模量上,皮尔逊相关系数均优于CNN(p < 0.05)。结论:oNLI框架实现了30,000倍速度提升的实时MRE反演,性能超越基于CNN的方法,并保持了传统NLI在脑部的精细空间精度。
原文摘要 · Abstract (English)
$\textbf{Purpose:}$ To develop and evaluate an operator learning framework for nonlinear inversion (NLI) of brain magnetic resonance elastography (MRE) data, which enables real-time inversion of elastograms with comparable spatial accuracy to NLI. $\textbf{Materials and Methods:}$ In this retrospective study, 3D MRE data from 61 individuals (mean age, 37.4 years; 34 female) were used for development of the framework. A predictive deep operator learning framework (oNLI) was trained using 10-fold cross-validation, with the complex curl of the measured displacement field as inputs and NLI-derived reference elastograms as outputs. A structural prior mechanism, analogous to Soft Prior Regularization in the MRE literature, was incorporated to improve spatial accuracy. Subject-level evaluation metrics included Pearson's correlation coefficient, absolute relative error, and structural similarity index measure between predicted and reference elastograms across brain regions of different sizes to understand accuracy. Statistical analyses included paired t-tests comparing the proposed oNLI variants to the convolutional neural network baselines. $\textbf{Results:}$ Whole brain absolute percent error was 8.4 $\pm$ 0.5 ($μ'$) and 10.0 $\pm$ 0.7 ($μ''$) for oNLI and 15.8 $\pm$ 0.8 ($μ'$) and 26.1 $\pm$ 1.1 ($μ''$) for CNNs. Additionally, oNLI outperformed convolutional architectures as per Pearson's correlation coefficient, $r$, in the whole brain and across all subregions for both the storage modulus and loss modulus (p < 0.05). $\textbf{Conclusion:}$ The oNLI framework enables real-time MRE inversion (30,000x speedup), outperforming CNN-based approaches and maintaining the fine-grained spatial accuracy achievable with NLI in the brain.
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