International Graduate School of English

The study proposes PIRTA, a retrieval-augmented generation framework in which a 3D ViT encoder pretrained with large-scale MAE self-supervision retrieves clinically similar 3D DWI/ADC volumes in the image domain, and their paired clinician-authored reports ground LLaMA3-8B-Instruct report generation, avoiding explicit image-text alignment; on a 1,831-case multi-institutional internal cohort, a 580-case privacy-preserving external cohort, and the 206-case public ISLES benchmark, PIRTA achieves strong image-domain retrieval (internal mAP@1 of 94.0%) and consistently improves ischemic-territory accuracy, a clinically grounded surrogate for factuality, over direct image-to-text 2D baselines, leading the strongest 2D baseline by +57.2 / +34.5 / +30.6 multi-class accuracy points.

The study proposes PIRTA, a retrieval-augmented generation framework in which a 3D ViT encoder pretrained with large-scale MAE self-supervision retrieves clinically similar 3D DWI/ADC volumes in the image domain, and their paired clinician-authored reports ground LLaMA3-8B-Instruct report generation, avoiding explicit image-text alignment; on a 1,831-case multi-institutional internal cohort, a 580-case privacy-preserving external cohort, and the 206-case public ISLES benchmark, PIRTA achieves strong image-domain retrieval (internal mAP@1 of 94.0%) and consistently improves ischemic-territory accuracy, a clinically grounded surrogate for factuality, over direct image-to-text 2D baselines, leading the strongest 2D baseline by +57.2 / +34.5 / +30.6 multi-class accuracy points.