无需外部数据,高效提升临床磁共振图像的分辨率。
ECLARE: Efficient cross-planar learning for anisotropic resolution enhancement
- 利用自学习机制与切片轮廓估计,实现无外部数据的超分辨率重建
- 在真实仿真数据上,信号恢复与下游任务表现均优于现有方法
- 适合临床场景中厚切片、间隙大、非整数缩放的异向性图像处理
临床磁共振成像常以多层2D切片形式采集,虽利于扫描效率与信噪比,但导致3D分析算法性能下降,尤其在厚切片与切片间隙较大的情况下。现有超分辨率方法未能同时解决切片轮廓估计、切片间隙、域偏移及非整数上采样因子等问题。本文提出ECLARE(Efficient Cross-planar Learning for Anisotropic Resolution Enhancement),一种自监督超分辨率方法,通过从多切片2D MR数据中估计切片轮廓,训练网络学习同体积内低分辨率到高分辨率的平面块映射,并结合抗混叠处理。我们在真实且具有代表性的仿真数据上对比了ECLARE与三次B样条插值、SMORE及其他主流方法,结果表明其在信号恢复和下游任务中均显著优于其他方法。关键优势在于不依赖外部训练数据,避免了训练-测试域偏移问题。代码已开源:https://www.github.com/sremedios/eclare。
原文摘要 · Abstract (English)
In clinical imaging, magnetic resonance (MR) image volumes are often acquired as stacks of 2D slices with decreased scan times, improved signal-to-noise ratio, and image contrasts unique to 2D MR pulse sequences. While this is sufficient for clinical evaluation, automated algorithms designed for 3D analysis perform poorly on multi-slice 2D MR volumes, especially those with thick slices and gaps between slices. Super-resolution (SR) methods aim to address this problem, but previous methods do not address all of the following: slice profile shape estimation, slice gap, domain shift, and non-integer or arbitrary upsampling factors. In this paper, we propose ECLARE (Efficient Cross-planar Learning for Anisotropic Resolution Enhancement), a self-SR method that addresses each of these factors. ECLARE uses a slice profile estimated from the multi-slice 2D MR volume, trains a network to learn the mapping from low-resolution to high-resolution in-plane patches from the same volume, and performs SR with anti-aliasing. We compared ECLARE to cubic B-spline interpolation, SMORE, and other contemporary SR methods. We used realistic and representative simulations so that quantitative performance against ground truth can be computed, and ECLARE outperformed all other methods in both signal recovery and downstream tasks. Importantly, as ECLARE does not use external training data it cannot suffer from domain shift between training and testing. Our code is open-source and available at https://www.github.com/sremedios/eclare.
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