Liver MRI LI-RADS Lexicon for Vision-Language Model Explanation Generation (v2.0)

A structured terminology lexicon for LI-RADS major feature description in multiphase liver MRI, developed to guide lexicon-constrained explanation generation by vision-language models (VLMs). The lexicon defines standardized preferred terms, synonyms, absence phrases, and avoid terms for nine LI-RADS radiological features: arterial phase hyperenhancement (APHE), delayed capsule appearance, delayed washout, portal venous capsule appearance, portal venous washout, diffusion restriction, T2 hyperintensity, T1 native lesion signal, and intralesional fat. Version 2.0 incorporates expert radiologist review: CT-specific terms removed, chemical-shift sequences clarified, washout mechanism corrected, and informal phrases removed across all entries. The lexicon was grounded in LI-RADS v2021 guidelines (American College of Radiology) and supplementary MRI literature, and was validated through a blinded pairwise radiologist evaluation study comparing VLM-generated explanations with and without lexicon constraints. Developed at the Biomedical Imaging Group Rotterdam (BIGR), Erasmus MC, as part of a master's thesis on VLM-based liver lesion characterization (Erasmus MC, 2026).