ChatGPT Makes Medicine Easy to Swallow: An Exploratory Case Study on Simplified Radiology Reports

In plain words

Radiology reports, the written results of scans such as MRI or CT, are full of medical jargon. They are written for other doctors, so patients often find them hard to follow, and the talk with the doctor that would explain them is often delayed. A patient can now paste a report into a public chatbot and ask for it in plain language. This paper asks whether the result is trustworthy.

The authors wrote three fictitious reports, a knee MRI, a brain MRI and a cancer follow-up CT, and asked ChatGPT to explain each one to a child. They repeated the request 15 times per report and gave the results to 15 radiologists, who each checked a few of them. The radiologists judged whether the rewrites were factually correct, complete and not potentially harmful, and they highlighted wrong passages in the text.

Most radiologists found the rewrites correct, complete and not harmful. They also found wrong statements, invented findings, and important results that had been dropped. The authors see real promise for patients, but they say that a radiologist should check such rewrites before a patient relies on them.

TL;DR

• Exploratory study, not a new model: ChatGPT (December 15, 2022 interface) simplified three fictitious radiology reports, 15 times each, with one prompt §3.2.
• 15 radiologists rated 45 simplified reports for factual correctness, completeness and potential harm; medians were 2 (agree), 2 (agree) and 4 (disagree) tab. 1.
• Errors were reported (misread terms, imprecise and invented statements, missed findings); the authors recommend physician oversight §4.2 §5.2.
• Results are author-reported on a small, single-institution sample with no comparison system and no code.

Problem

Radiology findings are written in specialist language for clinicians, and readers without medical training often find them hard to follow §1. The introduction cites a study that found 4% of analysed reports readable by the average US adult §1 §2.3. Simplification could help patients, but a patient who simplifies a report alone has no expert to check the result §5.2.

The paper's concern is that ChatGPT was not trained for medical text simplification and can produce plausible text that is not true §1. No evaluation by radiologists of automatically simplified radiology reports was known to the authors §1 §2.3. The study asks whether the output is factually correct, complete and not potentially harmful §1.

Assumptions: the reports are fictitious and of moderate complexity §3.1, the model is used with its default interface settings (temperature cannot be set) §3.2, and quality is judged only from a radiologist's point of view §5.3.

Method

The study has four parts. The paper calls it a case study rather than an algorithm, so there is no model architecture or training step to implement.

1. Original reports. One radiologist, with 10 years of experience, invented three reports: Knee MRI, Head MRI (a follow-up) and Oncol. CT (a follow-up whole-body CT). All three have moderate complexity by the authors' definition §3.1. Full texts are in app. A.
2. Prompting. Each report is sent to the ChatGPT web interface (version December 15, 2022) with the request "Explain this medical report to a child using simple language:" followed by the report text §3.2. The prompt was picked by informal trial on a separate fictitious report, from six variants §3.2. fig. 1 shows an example.
3. Sampling. Each report is simplified 15 times, and the chat is restarted before each repeat so that earlier turns do not influence the answer §3.2. This gives 45 simplified reports §3.2.
4. Questionnaire. Each radiologist receives the three original reports and one randomly chosen simplified version of each. Each radiologist gets different versions §3.3. For each simplified report they rate three statements on a 5-point Likert scale and give a free-text follow-up §3.3 fig. 5 fig. 6. fig. 2 shows the pipeline.

Definitions used in the questionnaire §3.3:

• Factual correctness: not further specified by the authors.
• Completeness: a complete report includes all key medical information that is relevant to the patient.
• Harm: the potential that a reader draws wrong conclusions, leading to physical or psychological harm or to an unwanted change in therapy or compliance.

The statements (quoted because the wording matters) are: "The simplified radiological report is factually correct."; "Relevant medical information for the patient is included in the simplified radiological report."; and "The simplified report leads patients to draw wrong conclusions, which might result in physical and/or psychological harm." Each has a follow-up asking the rater to highlight wrong text, list missing information, or list harmful conclusions, where applicable §3.3.

Evaluation §3.4: for each statement and each original report, the authors compute median, Q1, Q3, IQR, minimum, maximum, mean and standard deviation of the ordinal ratings. They count words in each report. They transcribe all highlights and free-text answers, and they group the free-text answers by content inductively §3.4.

# Generate simplified reports  [§3.2]
# Input:  originals (3 reports), prompt (text), repeats = 15
# Output: 15 simplified reports per original (45 in total)

def generate_simplified_reports(originals, prompt, repeats):
    # Keep the outputs keyed by the original report  [§3.2]
    simplified = {}
    for original in originals:
        simplified[original.name] = []
        for repeat in range(repeats):
            # Start a fresh chat so earlier turns cannot leak in  [§3.2]
            reply = chatgpt_web(prompt + original.text, new_chat=True)
            simplified[original.name].append(reply)
    return simplified

# Build one questionnaire per radiologist  [§3.3]
# Input:  originals, simplified (15 per original), radiologist
# Output: 3 blocks, each = original + one random simplified version

def build_questionnaire(originals, simplified, radiologist):
    # Each block pairs an original with one random generation  [§3.3]
    blocks = []
    for original in originals:
        version = random_choice(simplified[original.name])
        blocks.append((original, version))
    return blocks

Hyperparameters

The paper has no training hyperparameters. The table lists the settings that determine the output or the study design.

Results

Author-reported. Setup: 15 radiologists, 3 fictitious reports, 45 ChatGPT simplifications (December 15, 2022 interface). No baseline system or alternative simplifier was compared §3.2 §3.3 §4.

Overall ratings across all 45 simplified reports tab. 1. 1 = strongly agree, 5 = strongly disagree.

Per original report tab. 2:

Free-text follow-ups that gave evidence tab. 3:

Free-text findings, grouped by content §4.2:

• Incorrect passages: misinterpreted medical terms (for example "DD" read as a final diagnosis), imprecise wording, hallucinated findings, odd wording and a grammatical error §4.2.1.
• Missing information: missed findings and unspecific locations §4.2.2.
• Potential harm: mostly the same passages again, such as lymph nodes described as possibly cancerous and a "small growth" that was in fact almost doubled §4.2.3 §5.1.3.

Word counts tab. 4:

Other reported results: the model never refused a request or flagged an answer as possibly wrong §5.1. The radiologists' median experience was 5 years, with IQR 9 §4.

Paper vs code

No official code. The paper and its bibliography link no repository. A GitHub repository search for "simplified radiology reports chatgpt" and "jeblick radiology" returned zero results, so no code was used. The questionnaire is printed as figures fig. 5 fig. 6, and the raw answers are in tab. 5.

Pitfalls

• Not reproducible as written. The model was accessed through the ChatGPT web interface, the sampling settings cannot be changed, and the version is dated December 15, 2022 §3.2. The authors say it is "difficult, if not almost impossible" to reproduce an output §5.2. A re-run uses a different model snapshot, so treat the numbers as a snapshot.
• The prompt is not validated. It was chosen from six informal trials on one other fictitious report, and the authors do not claim it is the best prompt §3.2 §5.3.
• Small, fictitious sample. Three reports and 15 raters from one radiology department §5.3. The reports are fictitious and of medium complexity, and the authors say it is unclear how simpler or more complex reports would be rated §3.1 §5.3.
• Text and table disagree on the top harm score. §4.1 and §5.1.3 say that "Strongly Disagree" was never chosen for harm. tab. 1 has a maximum of 5 for harm, the per-report table tab. 2 has 5 in every report, and the raw answers tab. 5 contain 5s. Use the table values.
• Text and table disagree on the harm share. §5.1.3 says "about half" of the radiologists found critical statements. tab. 3 reports 36% listed harmful conclusions. The paper gives no explanation for the difference.
• Harm points the other way. The harm statement is worded as "leads patients to draw wrong conclusions". A median of 4 (disagree) means low perceived harm, while a median of 2 on factual correctness means agreement. Do not compare the two directly.
• Labels differ. The text uses "Fully agree" and "Fully disagree" §4.1, but tab. 1 uses "Strongly agree" and "Strongly disagree" for the same codes.
• Means and SDs of ordinal ratings. The paper reports them §3.4. Medians and quartiles are the safer summary.
• Experience summary is unclear. "median (IQR) experience of 5 (9) years" §4 gives the IQR width, but not the quartiles.
• Unclear sentence on who wrote the reports. §5.3 says "the radiologist who generated the simplified reports is German, i.e., not a native English speaker". ChatGPT generated the simplified reports, and a radiologist wrote the original reports §3.1, so the sentence probably means the originals. It also notes a German abbreviation ("Z.n.") in the original reports. The paper does not say more.
• Free-text highlights were transcribed by hand §3.4. Category counts are not given, only the examples and the percentages in tab. 3.
• Variability is covered, not controlled. The 15 repeats are meant to give "good coverage of its generative capability" §3.2. The paper does not select or rank outputs, so each report's ratings are an average over several answers.

Lineage

• Builds on: GPT-3 and InstructGPT's human-feedback training, as background on ChatGPT's design §2.2; earlier radiology-report simplification and summarisation work §2.3.
• Compared against: nothing in the study. The introduction names a free simplification service only as context §1.
• Superseded by: not stated in the paper.