Predicting diffusion-FLAIR mismatch from B1000 and ADC without FLAIR: A deep learning-based approach

Diffusion-FLAIR mismatch (DFM), defined as the discrepancy between diffusion-weighted imaging (DWI) and FLAIR sequences, is a key imaging biomarker used to identify patients with unclear symptom onset or those likely to benefit from recanalization therapy. However, FLAIR imaging is often limited in acute clinical settings due to time constraints, patient instability, or scanner availability. Therefore, alternative approaches to assess DFM without relying on FLAIR are needed. This study aimed to develop a deep learning model that predicts DFM using only B1000 and apparent diffusion coefficient (ADC) images, and to evaluate its performance. This study was conducted using multicenter stroke registry-based cohorts. After excluding cases not suitable for analysis, 2,369 cases were included in the derivation cohort for model development, and 679 cases from two independent stroke centers were included as external validation cohorts. Model performance was assessed based on two binary classification schemes. The Broad classification included all non-match cases, comprising both clearly defined mismatches and ambiguous cases with subtle or focal FLAIR changes, while the Focused classification excluded such ambiguous cases, including only clearly defined match and mismatch instances. In the Focused classification setting, the AI model achieved an AUROC of 0.92 (95% CI: 0.88-0.95) on the external validation dataset, significantly outperforming the average AUROC of human experts, which was 0.82 (95% CI: 0.77-0.87) (p < 0.001, AUROC difference 0.10). Overall, the Focused classification yielded higher performance than the Broad classification, and this trend was consistent for both the AI model and human readers. We developed a deep learning-based classifier capable of predicting DFM using only B1000 and ADC images, without requiring FLAIR. The model outperformed human experts and demonstrates potential as a complementary diagnostic tool in acute stroke settings where FLAIR imaging is unavailable, supporting its future integration into decision-support systems.