Calibrated pneumonia detection in chest X-rays via cross-attention fusion of foundation model features and lung-masked representations
摘要
Each year, pneumonia is responsible for more than 2.2 million deaths. Although deep learning has helped to analyze chest X-rays (CXRs), current systems approach segmentation and classification separately. They also use basic combination methods and give clinically inappropriate overconfident predictions.
PurposeTo formulate and verify a pneumonia detection framework with the clinically safe deployment of anatomically informed segmentation, cross-attention fusion, and ensemble calibration.
MethodsWe created a MedSAM-guided Transformer enhanced U-Net segmentation framework combined with cross attention from dual CheXFound branch encoders. Training was done on the RSNA and NIH ChestX-ray14 datasets (n=28,526), and external validation was done on the CheXpert and COVIDx datasets. The ensembles of five models with temperature scaling improved calibration. Key metrics to evaluate the performance of the models include AUROC, expected calibration error (ECE), and radiologist Grad-CAM++ annotations for interpretability validation.
ResultsOn combined test sets (n=6,112), the framework achieved AUROC 0.973 [95% CI: 0.969–0.977], significantly outperforming ResNet-50 (0.921), DenseNet-121 (0.934), ViT-B/16 (0.947), and CheXFound (0.958; all p<0.05). External validation demonstrated robust generalization (CheXpert: 0.961; COVIDx: 0.958). Cross-attention fusion outperformed concatenation (0.973 vs. 0.963, p=0.008). Ensemble calibration reduced ECE by 62% (0.021→0.008). Grad-CAM++ showed 87.3% overlap with radiologist annotations.
ConclusionsThis calibration-aware framework demonstrates clinically relevant performance through unified integration of segmentation, validated interpretability, and trustworthy probability estimation, advancing development of safe AI-assisted pneumonia screening systems.