arXiv:2505.04963cs.CV2025-05ICCV被引 3

ViCTr可生成高保真、病灶可控的肝脏纤维化MRI,且推理仅需4步。

ViCTr: Vital Consistency Transfer for Pathology Aware Image Synthesis

  • 用修正流+修正扩散模型,分两阶段训练提升图像真实度。
  • 合成肝硬化MRI的医学弗雷歇距离达17.01,比现有方法低28%。
  • 支持病灶严重程度分级控制,适合医疗数据增强与研究使用。

由于标注病理数据有限、模态域差距以及弥漫性病灶(如肝硬化)建模复杂,医学图像合成仍具挑战。现有方法常难以兼顾解剖结构真实性和病灶表征,依赖自然图像先验或低效多步采样。本文提出ViCTr(Vital Consistency Transfer),一种结合修正流轨迹与Tweedie修正扩散过程的两阶段框架,实现高保真、病灶感知的图像合成。首先在ATLAS-8k数据集上使用弹性权重保持(EWC)预训练,以保护关键解剖结构;随后通过低秩适应(LoRA)模块进行对抗性微调,精确控制病灶严重程度。通过在线性轨迹框架中重构Tweedie公式,ViCTr支持单步采样,将推理步数从50降至4,且不牺牲解剖真实性。在BTCV(CT)、AMOS(MRI)和CirrMRI600+(肝硬化)数据集上评估,结果表明其性能达到当前最优:肝硬化合成的医学弗雷歇初始距离(MFID)为17.01,较现有方法降低28%;用于数据增强时,使nnUNet分割的平均骰率(mDSC)提升+3.8%。放射科医生评审显示,生成的肝硬化MRI与真实扫描临床无异。据我们所知,ViCTr是首个实现细粒度、病灶感知、可分级控制的MRI合成方法,填补了人工智能医学影像研究中的关键空白。

原文摘要 · Abstract (English)

Synthesizing medical images remains challenging due to limited annotated pathological data, modality domain gaps, and the complexity of representing diffuse pathologies such as liver cirrhosis. Existing methods often struggle to maintain anatomical fidelity while accurately modeling pathological features, frequently relying on priors derived from natural images or inefficient multi-step sampling. In this work, we introduce ViCTr (Vital Consistency Transfer), a novel two-stage framework that combines a rectified flow trajectory with a Tweedie-corrected diffusion process to achieve high-fidelity, pathology-aware image synthesis. First, we pretrain ViCTr on the ATLAS-8k dataset using Elastic Weight Consolidation (EWC) to preserve critical anatomical structures. We then fine-tune the model adversarially with Low-Rank Adaptation (LoRA) modules for precise control over pathology severity. By reformulating Tweedie's formula within a linear trajectory framework, ViCTr supports one-step sampling, reducing inference from 50 steps to just 4, without sacrificing anatomical realism. We evaluate ViCTr on BTCV (CT), AMOS (MRI), and CirrMRI600+ (cirrhosis) datasets. Results demonstrate state-of-the-art performance, achieving a Medical Frechet Inception Distance (MFID) of 17.01 for cirrhosis synthesis 28% lower than existing approaches and improving nnUNet segmentation by +3.8% mDSC when used for data augmentation. Radiologist reviews indicate that ViCTr-generated liver cirrhosis MRIs are clinically indistinguishable from real scans. To our knowledge, ViCTr is the first method to provide fine-grained, pathology-aware MRI synthesis with graded severity control, closing a critical gap in AI-driven medical imaging research.

医学图像合成肝硬化扩散模型数据增强

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