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InfoResearchPeer-reviewed

Adversarial robustness of deep learning-based thyroid nodule segmentation in ultrasound

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Summary

Researchers evaluated two black-box adversarial attacks against a U-Net model that segments thyroid nodules in B-mode ultrasound images, trained on cine-clips from 192 nodules. The spatial-domain attack SSAA reduced mean DSC from 0.76 to 0.47 while keeping SSIM at 0.94, and the frequency-domain attack FDUA reduced it to 0.65 (SSIM 0.82). Three inference-time defenses significantly recovered DSC against SSAA, with deterministic denoising giving the largest gain (+0.10), but none significantly improved results against FDUA.

Mitigation

The three inference-time mitigations evaluated were randomized preprocessing with test-time augmentation, deterministic input denoising, and stochastic ensemble inference with consistency-aware aggregation. They partially mitigated spatial-domain perturbations, but statistically significant DSC recovery was not demonstrated against frequency-domain perturbations.