IRM-UNet: backbone-agnostic implicit refinement for enhanced pancreatic CT segmentation
摘要
Accurate pancreatic segmentation in computed tomography (CT) remains challenging due to irregular morphology, low contrast, and blurred boundaries. Most segmentation backbones produce discrete, fixed-grid voxel predictions, which can lead to coarse contours and limited representation of subtle, continuous anatomical deformations. To mitigate this limitation, IRM-UNet is introduced as a backbone-agnostic refinement framework that augments segmentation backbones with an implicit neural representation (INR) module for sub-voxel boundary refinement. The main innovations are as follows: (1) Continuous boundary reconstruction: modeling pancreatic morphology in a continuous domain via an INR enables accurate delineation of complex boundaries; (2) Multi-scale feature fusion and uncertainty-aware sampling: multi-scale feature integration with uncertainty-aware sampling concentrates refinement on low-contrast and ambiguous regions, improving robustness; and (3) High-frequency detail enhancement: combining positional encoding with Fourier feature mapping projects low-dimensional coordinates into a higher-dimensional space, facilitating the representation of high-frequency boundary details. Experiments on the NIH pancreatic CT dataset yield a Dice coefficient of