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arXiv 2604.27101eess.IV

一种用于从LGE-MR图像中进行左心房壁约束瘢痕分割与定位的双阶段流程

A Two Stage Pipeline for Left Atrial Wall Constrained Scar Segmentation and Localization from LGE-MR Images

Bipasha Kundu, Cristian Linte

AI总结:

本文提出一种双阶段nnUNet框架,利用左心房解剖结构提升瘢痕分割与定位精度,通过几何感知输入和边界不确定性监督策略,提高分割准确性并降低误检率。

摘要:

准确分割和定位左心房(LA)消融瘢痕对于评估病变完整性和指导消融治疗至关重要。不完整或不连续的病变会增加治疗复发率,而不准确的定位会误导治疗计划。然而,可靠地量化和定位LGE-MR图像中的瘢痕具有挑战性。严重的瘢痕体素类别不平衡、左心房壁的薄结构以及弱的组织对比度常常导致不现实的瘢痕预测。本文提出了一种双阶段基于nnUNet的框架,考虑左心房解剖结构以帮助更精确的瘢痕定位和分割。第一阶段训练一个nnUNet模型分割左心房腔体。第二阶段从预测的解剖结构中推导出患者特异性的腔体和壁的有符号距离图(SDMs),作为几何感知输入,并明确编码每个体素相对于心房腔体和壁的有符号空间关系。这种方法将瘢痕分割从单纯的强度分类任务转变为解剖条件化的定位任务,提供连续的空间先验,稳定学习薄的左心房壁并抑制拓扑无效的预测。为进一步解决边界模糊性,我们引入了壁ROI-加权损失,结合边界不确定性感知监督策略,限制学习到心房壁,同时考虑严重的类别不平衡。我们在LAScarQS 2022数据集上评估了我们的方法,取得了Dice系数为61.1%和ASSD为1.711mm的性能。我们的可靠且有效的框架通过几何感知监督强制解剖有效性,提高了瘢痕分割和定位的准确性,并显著降低了远离心房壁的误检率。

英文摘要:

Accurate segmentation and localization of left atrial (LA) ablation scars from Late gadolinium enhancement (LGE)-MRI is essential for assessing the lesion completeness and guiding ablation therapy. Incomplete or discontinuous lesions can increase the recurrence rate of the therapy and inaccurate localization can misguide treatment planning. However, reliable quantification and localization of scar in LGE-MRI is challenging. The severely class imbalanced scar voxels, thin structure of the LA wall, and weak tissue contrast often lead to unrealistic scar predictions. In this paper, we propose a two stage nnUNet based framework that takes LA anatomy into account to help with more precise scar localization and segmentation. In the first stage, an nnUNet model is trained to segment the LA cavity. In the second stage, patient specific cavity and wall signed distance maps (SDMs) are derived from the predicted anatomy to use as geometry aware inputs, and explicitly encode each voxel's signed spatial relationship to the atrial cavity and wall. This approach transforms scar segmentation from a solely intensity-based classification into anatomy-conditioned localization task, providing a continuous spatial prior that stabilizes learning for the thin atrial wall and suppresses topologically invalid predictions. To further address boundary ambiguity, we introduce a wall ROI-masked weighted loss combined with boundary uncertainty-aware supervision strategy that restricts learning to the atrial wall, while accounting for severe class imbalance. We evaluated our approach on the LAScarQS 2022 dataset and achieved a Dice of 61.1% and ASSD of 1.711mm. Our reliable and effective framework improves scar segmentation and localization accuracy by enforcing anatomical validity through geometry-aware supervision, and lowering the false positive detections far away from the atrial wall.

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