arXiv:2502.07145cs.CV2025-02被引 3

无需标注即可从表面网格学习人体结构统计模型,还支持不确定性量化。

Mesh2SSM++: A Probabilistic Framework for Unsupervised Learning of Statistical Shape Model of Anatomies from Surface Meshes

  • 通过无监督方法直接从网格估计形状对应关系,无需预设模板。
  • 在多种解剖结构上优于现有方法,且能量化数据固有不确定性。
  • 适合医学影像分析、临床决策支持等需要可靠形状建模的场景。

解剖评估对理解生理状态、诊断异常和指导医疗干预至关重要。统计形状建模(SSM)在此过程中发挥关键作用,可从MRI和CT扫描中提取定量形态描述符,全面描述群体内解剖变异。然而,SSM的有效性依赖于模型质量与鲁棒性。尽管深度学习在学习复杂非线性形状表示方面展现潜力,但现有模型仍存在局限,通常需依赖预设形状模型进行训练。为此,我们提出Mesh2SSM++,一种新型无监督方法,可直接从表面网格估计对应关系。该方法利用无监督、排列不变的表示学习,将模板点云变形至个体特异性网格,形成基于对应关系的形状模型。此外,其概率框架可学习特定人群模板,降低模板选择带来的偏差。一个关键优势是能够量化意外不确定性(aleatoric uncertainty),捕捉数据内在变异性,对确保临床任务中可靠预测和稳健决策至关重要,尤其在成像条件困难时。通过在多种解剖结构、评估指标和下游任务上的广泛验证,我们证明Mesh2SSM++优于现有方法。其直接处理网格的能力、计算效率及概率框架带来的可解释性,使其成为传统与深度学习驱动的SSM方法的有力替代方案。

原文摘要 · Abstract (English)

Anatomy evaluation is crucial for understanding the physiological state, diagnosing abnormalities, and guiding medical interventions. Statistical shape modeling (SSM) is vital in this process. By enabling the extraction of quantitative morphological shape descriptors from MRI and CT scans, SSM provides comprehensive descriptions of anatomical variations within a population. However, the effectiveness of SSM in anatomy evaluation hinges on the quality and robustness of the shape models. While deep learning techniques show promise in addressing these challenges by learning complex nonlinear representations of shapes, existing models still have limitations and often require pre-established shape models for training. To overcome these issues, we propose Mesh2SSM++, a novel approach that learns to estimate correspondences from meshes in an unsupervised manner. This method leverages unsupervised, permutation-invariant representation learning to estimate how to deform a template point cloud into subject-specific meshes, forming a correspondence-based shape model. Additionally, our probabilistic formulation allows learning a population-specific template, reducing potential biases associated with template selection. A key feature of Mesh2SSM++ is its ability to quantify aleatoric uncertainty, which captures inherent data variability and is essential for ensuring reliable model predictions and robust decision-making in clinical tasks, especially under challenging imaging conditions. Through extensive validation across diverse anatomies, evaluation metrics, and downstream tasks, we demonstrate that Mesh2SSM++ outperforms existing methods. Its ability to operate directly on meshes, combined with computational efficiency and interpretability through its probabilistic framework, makes it an attractive alternative to traditional and deep learning-based SSM approaches.

统计形状模型无监督学习医学影像不确定性量化

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