Standard AUC Evaluation Cannot Detect Shortcut Learning in Medical Image Classifiers: A Controlled Cross-Domain Study
Investigates why standard within-distribution Area Under the ROC Curve (AUC) fails to detect when convolutional neural networks latch onto spurious background artifacts (shortcuts) rather than true clinical pathology. We demonstrate cross-domain performance collapse in external cohorts despite near-perfect in-distribution AUC. Investigates why standard in-distribution AUC fails to detect shortcut artifacts in CNNs, resulting in cross-domain diagnostic collapse.