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arXiv 2509.23176cs.CV

面向域偏移下鲁棒脑部MRI分割的置信度校准正则化方法

Confidence-Calibrating Regularization for Robust Brain MRI Segmentation Under Domain Shift

Institute of Business Administration(商业管理学院)

Behraj Khan, Tahir Qasim Syed, Syed Ahmad Chan Bukhari

AI总结:

针对SAM用于脑部MRI分割时的域偏移与过置信问题,提出轻量适配框架CalSAM,通过FIP与CMP仅微调解码器,在多数据集偏移任务上显著提升分割准确率与置信度校准度。

摘要:

Segment Anything Model(SAM)在自然图像上展现出强大的零样本性能,但应用于医学影像时会面临域偏移问题及过置信缺陷。本文提出CalSAM,这是一种轻量型适配框架:其一,通过在3D特征图上计算的特征Fisher信息惩罚项(FIP)降低编码器对域偏移的敏感性;其二,通过置信度失配惩罚项(CMP)惩罚体素级的过置信误差。组合损失函数\boldsymbol{\textit{L}}_{\text{CalSAM}}仅微调掩码解码器,同时保持SAM的编码器冻结。在跨中心及扫描仪偏移的评估中,CalSAM显著提升了准确率与校准度:例如在BraTS扫描仪拆分(Siemens→GE)任务上,CalSAM的DSC相对提升7.4%(80.1% vs. 74.6%),HD95降低26.9%(4.6 mm vs. 6.3 mm),ECE降低39.5%(5.2% vs. 8.6%);在ATLAS-C(运动伪影)任务上,CalSAM的DSC相对提升5.3%(75.9%),ECE降低32.6%(5.8%)。 ablation实验表明,FIP与CMP带来互补增益(p<0.01),且Fisher惩罚项仅产生约15%的适度训练时间开销。因此,CalSAM在保留SAM编码器冻结的计算优势的同时,为脑部MRI分割提供了更优的域泛化能力与更准确的不确定性估计。

英文摘要:

The Segment Anything Model (SAM) exhibits strong zero-shot performance on natural images but suffers from domain shift and overconfidence when applied to medical volumes. We propose \textbf{CalSAM}, a lightweight adaptation framework that (i) reduces encoder sensitivity to domain shift via a \emph{Feature Fisher Information Penalty} (FIP) computed on 3D feature maps and (ii) penalizes overconfident voxel-wise errors through a \emph{Confidence Misalignment Penalty} (CMP). The combined loss, \(\mathcal{L}_{\mathrm{CalSAM}}\) fine-tunes only the mask decoder while keeping SAM's encoders frozen. On cross-center and scanner-shift evaluations, CalSAM substantially improves accuracy and calibration: e.g., on the BraTS scanner split (Siemens$\to$GE) CalSAM shows a $+7.4\%$ relative improvement in $\mathrm{DSC}$ (80.1\% vs.\ 74.6\%), a $-26.9\%$ reduction in $\mathrm{HD95}$ (4.6 mm vs.\ 6.3 mm), and a $-39.5\%$ reduction in $\mathrm{ECE}$ (5.2\% vs.\ 8.6\%). On ATLAS-C (motion corruptions), CalSAM achieves a $+5.3\%$ relative improvement in $\mathrm{DSC}$ (75.9\%) and a $-32.6\%$ reduction in $\mathrm{ECE}$ (5.8\%). Ablations show FIP and CMP contribute complementary gains ($p<0.01$), and the Fisher penalty incurs a modest $\sim$15\% training-time overhead. CalSAM therefore delivers improved domain generalization and better-calibrated uncertainty estimates for brain MRI segmentation, while retaining the computational benefits of freezing SAM's encoder.

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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