Class Imbalance Correction for Improved Universal Lesion Detection and Tagging in CT
The DeepLesion dataset exhibits severe fine-grained class imbalance across anatomical regions, per-patient lesion counts, and lesion sizes, significantly hindering multi-class lesion detection and anatomical localization in CT imaging. To address this, we propose the first multi-dimensional data rebalancing paradigm tailored for joint lesion detection and anatomical localization—built upon the VFNet framework. We systematically compare hierarchical sampling strategies: anatomical region–based, patient-level, and lesion-size–based sampling, and—crucially—first identify and explicitly model DeepLesion’s three-tiered imbalance structure. Additionally, we introduce a standardized radiology report template, specifically structuring the “lesion” subsection to support rigorous data curation. Experiments demonstrate substantial improvements: on lesions ≥1 cm, sensitivity reaches 80% (bone), 77% (kidney), 70% (soft tissue), and 83% (pelvis)—all markedly surpassing random-sampling baselines. Notably, lesion-size balancing further boosts recall across all categories.