Pranav Rajpurkar


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Style-Aware Radiology Report Generation with RadGraph and Few-Shot Prompting
Benjamin Yan | Ruochen Liu | David Kuo | Subathra Adithan | Eduardo Reis | Stephen Kwak | Vasantha Venugopal | Chloe O’Connell | Agustina Saenz | Pranav Rajpurkar | Michael Moor
Findings of the Association for Computational Linguistics: EMNLP 2023

Automatically generated reports from medical images promise to improve the workflow of radiologists. Existing methods consider an image-to-report modeling task by directly generating a fully-fledged report from an image. However, this conflates the content of the report (e.g., findings and their attributes) with its style (e.g., format and choice of words), which can lead to clinically inaccurate reports. To address this, we propose a two-step approach for radiology report generation. First, we extract the content from an image; then, we verbalize the extracted content into a report that matches the style of a specific radiologist. For this, we leverage RadGraph—a graph representation of reports—together with large language models (LLMs). In our quantitative evaluations, we find that our approach leads to beneficial performance. Our human evaluation with clinical raters highlights that the AI-generated reports are indistinguishably tailored to the style of individual radiologist despite leveraging only a few examples as context.

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Exploring the Boundaries of GPT-4 in Radiology
Qianchu Liu | Stephanie Hyland | Shruthi Bannur | Kenza Bouzid | Daniel Castro | Maria Wetscherek | Robert Tinn | Harshita Sharma | Fernando Pérez-García | Anton Schwaighofer | Pranav Rajpurkar | Sameer Khanna | Hoifung Poon | Naoto Usuyama | Anja Thieme | Aditya Nori | Matthew Lungren | Ozan Oktay | Javier Alvarez-Valle
Proceedings of the 2023 Conference on Empirical Methods in Natural Language Processing

The recent success of general-domain large language models (LLMs) has significantly changed the natural language processing paradigm towards a unified foundation model across domains and applications. In this paper, we focus on assessing the performance of GPT-4, the most capable LLM so far, on the text-based applications for radiology reports, comparing against state-of-the-art (SOTA) radiology-specific models. Exploring various prompting strategies, we evaluated GPT-4 on a diverse range of common radiology tasks and we found GPT-4 either outperforms or is on par with current SOTA radiology models. With zero-shot prompting, GPT-4 already obtains substantial gains ( 10% absolute improvement) over radiology models in temporal sentence similarity classification (accuracy) and natural language inference (F1). For tasks that require learning dataset-specific style or schema (e.g. findings summarisation), GPT-4 improves with example-based prompting and matches supervised SOTA. Our extensive error analysis with a board-certified radiologist shows GPT-4 has a sufficient level of radiology knowledge with only occasional errors in complex context that require nuanced domain knowledge. For findings summarisation, GPT-4 outputs are found to be overall comparable with existing manually-written impressions.


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Combining Automatic Labelers and Expert Annotations for Accurate Radiology Report Labeling Using BERT
Akshay Smit | Saahil Jain | Pranav Rajpurkar | Anuj Pareek | Andrew Ng | Matthew Lungren
Proceedings of the 2020 Conference on Empirical Methods in Natural Language Processing (EMNLP)

The extraction of labels from radiology text reports enables large-scale training of medical imaging models. Existing approaches to report labeling typically rely either on sophisticated feature engineering based on medical domain knowledge or manual annotations by experts. In this work, we introduce a BERT-based approach to medical image report labeling that exploits both the scale of available rule-based systems and the quality of expert annotations. We demonstrate superior performance of a biomedically pretrained BERT model first trained on annotations of a rule-based labeler and then finetuned on a small set of expert annotations augmented with automated backtranslation. We find that our final model, CheXbert, is able to outperform the previous best rules-based labeler with statistical significance, setting a new SOTA for report labeling on one of the largest datasets of chest x-rays.


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Know What You Don’t Know: Unanswerable Questions for SQuAD
Pranav Rajpurkar | Robin Jia | Percy Liang
Proceedings of the 56th Annual Meeting of the Association for Computational Linguistics (Volume 2: Short Papers)

Extractive reading comprehension systems can often locate the correct answer to a question in a context document, but they also tend to make unreliable guesses on questions for which the correct answer is not stated in the context. Existing datasets either focus exclusively on answerable questions, or use automatically generated unanswerable questions that are easy to identify. To address these weaknesses, we present SQuADRUn, a new dataset that combines the existing Stanford Question Answering Dataset (SQuAD) with over 50,000 unanswerable questions written adversarially by crowdworkers to look similar to answerable ones. To do well on SQuADRUn, systems must not only answer questions when possible, but also determine when no answer is supported by the paragraph and abstain from answering. SQuADRUn is a challenging natural language understanding task for existing models: a strong neural system that gets 86% F1 on SQuAD achieves only 66% F1 on SQuADRUn. We release SQuADRUn to the community as the successor to SQuAD.


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SQuAD: 100,000+ Questions for Machine Comprehension of Text
Pranav Rajpurkar | Jian Zhang | Konstantin Lopyrev | Percy Liang
Proceedings of the 2016 Conference on Empirical Methods in Natural Language Processing