RadTimeline: Timeline Summarization for Longitudinal Radiological Lung Findings
Summary
Radiologists and clinicians must follow how lung findings change across a patient's successive imaging reports. Doing this by hand is slow and mentally taxing, and free-text AI summaries are hard to verify. The authors recast multi-report summarization as building a two-dimensional timeline table. Columns are dated exams, cells hold individual lung findings from each report, and rows track one finding's evolution under a descriptive row header.
Their generation pipeline uses off-the-shelf LLMs without supervised training, in three stages:
- Extract findings from each report.
- Propose group names from the longitudinal record.
- Assign each finding to a group.
To evaluate this, they built RadTimeline, a small hand-corrected benchmark drawn from chest-related imaging reports. They also proposed metrics for finding factuality, overgeneration, name quality and grouping.
Experiments compare LLMs of different sizes and several prompting strategies. The intermediate naming step proves essential for good grouping. The strongest setup recovers nearly all relevant findings, though it adds some irrelevant ones, and groups findings about as well as human annotators. The format makes AI summaries easier to fact-check in high-stakes clinical settings.
Key points
- RadTimeline dataset: 10 patients from a UW Medicine lung cancer surveillance cohort, with 65 chest-related reports (chest CT, chest X-ray, abdomen CT).
- Each patient has 4–12 reports, with longitudinal text of 646–4625 tokens (mean 2055).
- Six patients developed lung cancer within 3 years; four had no cancer record.
- Annotation: gold timelines were made by hand-correcting LLM drafts, with two medical students and one medical doctor as annotators. Findings outside the lungs (e.g., the aorta) and device mentions are excluded.
- Models and evaluation: models compared include GPT-4o and Llama 3.1 8B Instruct. Findings are scored with ROUGE-L plus overgeneration, alongside group name quality and grouping metrics.
- Smaller model behavior: Llama 3.1 tends to produce more findings and group names, including content unrelated to the lungs.
- Role of group names: generated group names matter most for weaker LLMs and for embedding-based grouping.
Cite
@inproceedings{zhou2026radtimeline,
title = {{RadTimeline: Timeline Summarization for Longitudinal Radiological Lung Findings}},
author = {Zhou, Sitong and Yetisgen, Meliha and Ostendorf, Mari},
booktitle = {Proceedings of the Fifteenth Language Resources and Evaluation Conference},
year = {2026},
doi = {10.63317/32uhj8rx3u8f},
url = {https://doi.org/10.63317/32uhj8rx3u8f}
}References
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