用多视角对齐恢复脑部MRI模糊图像,提升病灶分割精度。
Anatomically Consistent Cross-Contrast Super-Resolution of Anisotropic Brain T2w MRI

- 通过跨视角特征对齐,从局部高分辨切片学习解剖对应关系。
- 在真实数据上使分割Dice提升至0.563,比基线提高约20%。
- 无需额外标注,可直接用于不同数据集,适合医学影像分析研究者。
T2加权脑部MRI提供对液体敏感的软组织对比度,对神经肿瘤学和放疗规划至关重要。但其扫描采用各向异性体素,冠状面和矢状面显示模糊或阶梯状,掩盖微小结构并削弱三维分析效果。本文提出VIPP-SR(视图无关分块投影超分辨率)框架,无需各向同性真实标签即可恢复现有各向异性T2w图像的层间分辨率。该方法首先训练视图无关分块生成器(VIP-GAN),从高分辨率轴向切片中学习高分辨T1c与低分辨T2w间的局部解剖对应关系。随后将训练好的生成器应用于T1c图像的轴向、冠状面和矢状面,生成三个正交方向的T2w估计。通过形状保持分块和深层跳跃消除,抑制视图特异性偏差,迫使生成器学习局部特征表示,实现零样本跨平面迁移。核心在于基于投影的优化机制,在三视图间强制解剖一致性,通过平衡层间自洽性与单视图保真度融合结果。生成器在BraTS-MET上训练,评估在保留的BraTS-MET测试集和无重新训练的BraTS-GLI队列上进行跨队列泛化性测试。结果表明,相比真实各向异性T2w基线,VIPP-SR显著提升下游分割性能:在BraTS-MET上平均标签Dice从0.330提升至0.465;在零样本场景下,于BraTS-GLI上从0.473提升至0.563。消融实验确认层间自洽性是性能提升的主要来源。
原文摘要 · Abstract (English)
T2-weighted (T2w) brain MRI provides fluid-sensitive soft-tissue contrast that is important for neuro-oncology and radiotherapy planning. However, T2w scans are acquired with anisotropic voxels and appear blurred or stair-stepped on coronal and sagittal views, which obscures small structures and weakens any downstream 3D analysis. We propose VIPP-SR (View-Independent Patched Projection Super-Resolution), a cross-contrast guided super-resolution framework that restores the inter-plane resolution of an existing anisotropic T2w volume without an isotropic ground-truth T2w. VIPP-SR first trains a view-independent patched generator (VIP-GAN) to learn local T1c-to-T2w anatomical correspondence from high-resolution axial slices. The trained generator is then applied to axial, coronal, and sagittal views of the T1c volume to generate three orthogonal T2w estimates. Shape-preserving patching and deepest-skip removal reduce view-specific shortcuts, thereby constraining the generator to learn patch-local representations and enabling the zero-shot inter-plane transfer. Central to VIPP-SR, a projection-based optimization then enforces anatomical consistency across the three view-specific volumes, fusing them by balancing inter-plane self-consistency against per-view data fidelity. The generator is trained on BraTS-MET and evaluated on both the held-out BraTS-MET testing set and the BraTS-GLI cohort without retraining, assessing the cross-cohort generalizability. The results validate that VIPP-SR improves downstream segmentation over the real anisotropic T2w baseline, raising mean-label Dice from 0.330 to 0.465 on BraTS-MET and, zero-shot, from 0.473 to 0.563 on BraTS-GLI and ablation studies identify inter-plane self-consistency as the main source of the gain.
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