Semi-Supervised Natural Language Approach for Fine-Grained Classification of Medical Reports

TL;DR

This paper presents a semi-supervised approach using an encoder-language model trained on unlabeled radiology reports, enabling accurate classification of medical reports with less labeled data, and facilitating multimodal clinical analysis.

Contribution

Developed a semi-supervised pipeline that leverages unlabeled text data to improve fine-grained medical report classification with reduced labeled data requirements.

Findings

Achieved high AUCs of 0.98, 0.95, and 0.99 on three clinical datasets.

Demonstrated effective feature extraction from textual data for multimodal models.

Reduced labeled data needs for accurate disease classification.

Abstract

Although machine learning has become a powerful tool to augment doctors in clinical analysis, the immense amount of labeled data that is necessary to train supervised learning approaches burdens each development task as time and resource intensive. The vast majority of dense clinical information is stored in written reports, detailing pertinent patient information. The challenge with utilizing natural language data for standard model development is due to the complex nature of the modality. In this research, a model pipeline was developed to utilize an unsupervised approach to train an encoder-language model, a recurrent network, to generate document encodings; which then can be used as features passed into a decoder-classifier model that requires magnitudes less labeled data than previous approaches to differentiate between fine-grained disease classes accurately. The language model was trained on unlabeled radiology reports from the Massachusetts General Hospital Radiology Department (n=218,159) and terminated with a loss of 1.62. The classification models were trained on three labeled datasets of head CT studies of reported patients, presenting large vessel occlusion (n=1403), acute ischemic strokes (n=331), and intracranial hemorrhage (n=4350), to identify a variety of different findings directly from the radiology report data; resulting in AUCs of 0.98, 0.95, and 0.99, respectively, for the large vessel occlusion, acute ischemic stroke, and intracranial hemorrhage datasets. The output encodings are able to be used in conjunction with imaging data, to create models that can process a multitude of different modalities. The ability to automatically extract relevant features from textual data allows for faster model development and integration of textual modality, overall, allowing clinical reports to become a more viable input for more encompassing and accurate deep learning models.