Exploiting Longitudinal Context in Clinician-Verified Interactive Lesion Tracking

Researchers at the German Cancer Research Center (DKFZ) developed a new "Verified Tracking" paradigm for tumor lesion tracking across serial CT scans, achieving first place in the MICCAI autoPET IV challenge. The method allows clinicians to verify a registration-proposed prompt, which the model then uses alongside the baseline lesion appearance to resolve segmentation ambiguities, outperforming prior work in both fully automatic and verified tracking settings. The team also released PanTrack, a new longitudinal pancreatic cancer benchmark, to assess out-of-distribution generalization.

arXiv:2605.23118v1 Announce Type: new Abstract: Tracking tumor lesions across serial CT scans is essential for oncological response assessment. Existing automated methods face a fundamental trade-off: end-to-end trackers achieve high automation but offer no opportunity to correct silent tracking failures, while decoupled registration-segmentation pipelines permit user verification yet discard the lesion's prior appearance, limiting accuracy in ambiguous cases. In this work, we propose a Verified Tracking paradigm: a clinician verifies a registration-proposed prompt, which the model leverages alongside the baseline lesion appearance to resolve segmentation ambiguities. We present a unified framework combining early spatial prompt fusion with latent temporal difference weighting for longitudinally-informed segmentation. To address data scarcity, we leverage large-scale synthetic pretraining, proving essential for exploiting longitudinal context, improving performance by up to 4.5 Dice points over training from scratch. Our approach secured first place in the MICCAI autoPET IV challenge. We further curate and release PanTrack, a new longitudinal pancreatic cancer benchmark, to assess out-of-distribution generalization. Experiments show that our model outperforms prior work in both fully automatic and the proposed verified tracking setting offering a clinically safe middle ground between automation and control. Code, model and dataset will be released at https://github.com/MIC-DKFZ/LongiSeg