Impact of hospital-specific domain adaptation on BERT-based models to classify neuroradiology reports
摘要
To determine the effectiveness of hospital-specific domain adaptation through masked language modelling (MLM) on BERT-based models’ performance in classifying neuroradiology reports, and to compare these models with open-source large language models (LLMs).
Materials and methodsThis retrospective study (2008–2019) utilised 126,556 and 86,032 MRI brain reports from two tertiary hospitals—King’s College Hospital (KCH) and Guys and St Thomas’ Trust (GSTT). Various BERT-based models, including RoBERTa, BioBERT and RadBERT, underwent MLM on unlabelled reports from these centres. The downstream tasks were binary abnormality classification and multi-label classification. Performances of models with and without hospital-specific domain adaptation were compared against each other and LLMs on internal (KCH) and external (GSTT) hold-out test sets. Model performances for binary classification were compared using 2-way and 1-way ANOVA.
ResultsAll models that underwent hospital-specific domain adaptation performed better than their baseline counterparts (all p-values < 0.001). For binary classification, MLM on all available unlabelled reports (194,467 reports) yielded the highest balanced accuracies (KCH: mean 97.0 ± 0.4% (standard deviation), GSTT: 95.5 ± 1.0%), after which no differences between BERT-based models remained (1-way ANOVA, p-values > 0.05). There was a log-linear relationship between the number of reports and performance. LLama-3.0 70B was the best-performing LLM (KCH: 97.1%, GSTT: 94.0%). Multi-label classification demonstrated consistent performance improvements from MLM for all abnormality categories.
ConclusionHospital-specific domain adaptation should be considered best practice when deploying BERT-based models in new clinical settings. When labelled data is scarce or unavailable, LLMs can serve as a viable alternative, assuming adequate computational power is accessible.
Key Points