Topology-Driven Transferability Estimation for 3D Medical Vision Foundation Models
Existing methods for evaluating transferability in 3D medical image segmentation rely on time-consuming fine-tuning, which struggles to meet the stringent demands for boundary precision and anatomical consistency. This work proposes the first fine-tuning-free, topology-driven framework that aligns sparse features with semantic labels via minimum spanning trees (MSTs). It assesses transferability at dual scales—local boundary token separability (LBTC) and global representation topological divergence (GRTD)—and incorporates a task-adaptive gated fusion mechanism. Theoretically, we prove that the MST leakage rate constitutes a finite-sample lower bound of the Bayes error and reveal that randomly initialized decoders stabilize topological alignment. Evaluated on a large-scale benchmark encompassing 114,000 3D medical images, our method achieves state-of-the-art performance, improving the weighted Kendall metric by 0.36 on average and accelerating evaluation by 56×.