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arXiv 2410.20532eess.IVcs.CVcs.LG

广域搜索、深度聚焦:基于稀疏训练数据的自动化胎儿脑提取

Search Wide, Focus Deep: Automated Fetal Brain Extraction with Sparse Training Data

Harvard Medical School(哈佛医学院);Massachusetts General Hospital(麻省总医院);Pediatric Imaging Research Center(儿科影像研究中心)

Javid Dadashkarimi, Valeria Pena Trujillo, Camilo Jaimes, Lilla Zöllei, Malte Hoffmann

AI总结:

针对稀疏标记数据下胎儿脑MRI提取假阳性高的问题,提出结合广度优先搜索定位与深度聚焦滑动窗口细化的测试时策略,在合成数据训练下于多类胎儿MRI扫描中达到或超越现有方法水平。

摘要:

从全子宫MRI中自动化提取胎儿脑是一项具有挑战性的任务,原因在于胎儿头部尺寸、朝向多变,解剖结构复杂,且伪影普遍存在。尽管在合成图像上训练的深度学习(DL)模型在成人脑提取中已取得成功,但由于标记数据稀疏,将这些网络适配于胎儿MRI十分困难,会导致假阳性预测增多。为应对这一挑战,我们提出一种测试时策略,可降低在稀疏合成标记上训练的网络的假阳性率。该方法使用广度优先搜索(BFS)识别可能包含胎儿脑的子体积,随后通过深度聚焦滑动窗口(DFS)搜索优化提取结果,对预测结果进行池化以最大程度减少假阳性。我们利用少量胎儿脑标记图生成的合成图像,并添加随机几何形状作为增强,在不同窗口尺寸下训练模型。每个模型都在多样的头部位置和尺度下训练,包括仅含部分脑组织或不含脑组织的情况。我们的框架在孕晚期临床HASTE扫描上的表现与最先进的脑提取方法相当,而在孕中期HASTE扫描以及两个孕期的EPI扫描中,其Dice系数最高超出这些方法5%。我们的研究结果表明,滑动窗口方法结合多个在合成图像上训练的模型的预测,可通过逐步细化感兴趣区域、最大程度降低遗漏脑掩码切片或将其他组织误识别为脑组织的风险,提升脑提取的准确性。

英文摘要:

Automated fetal brain extraction from full-uterus MRI is a challenging task due to variable head sizes, orientations, complex anatomy, and prevalent artifacts. While deep-learning (DL) models trained on synthetic images have been successful in adult brain extraction, adapting these networks for fetal MRI is difficult due to the sparsity of labeled data, leading to increased false-positive predictions. To address this challenge, we propose a test-time strategy that reduces false positives in networks trained on sparse, synthetic labels. The approach uses a breadth-fine search (BFS) to identify a subvolume likely to contain the fetal brain, followed by a deep-focused sliding window (DFS) search to refine the extraction, pooling predictions to minimize false positives. We train models at different window sizes using synthetic images derived from a small number of fetal brain label maps, augmented with random geometric shapes. Each model is trained on diverse head positions and scales, including cases with partial or no brain tissue. Our framework matches state-of-the-art brain extraction methods on clinical HASTE scans of third-trimester fetuses and exceeds them by up to 5\% in terms of Dice in the second trimester as well as EPI scans across both trimesters. Our results demonstrate the utility of a sliding-window approach and combining predictions from several models trained on synthetic images, for improving brain-extraction accuracy by progressively refining regions of interest and minimizing the risk of missing brain mask slices or misidentifying other tissues as brain.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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