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RADAR learns 146 abdominal CT findings from the reports radiologists already wrote

Alibaba's DAMO Academy put RADAR's training code and pretrained checkpoints under Apache 2.0 on September 18, a day after the Science paper. The 146 in the coverage counts radiological findings, cancers among them.

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Photograph accompanying RADAR learns 146 abdominal CT findings from the reports radiologists already wrote
Photo: scmp.com

What happened

  • Researchers from Alibaba's DAMO Academy, Zhejiang University and affiliated hospitals released the code and checkpoints for RADAR, a model that screens abdominal CT scans for 146 clinical findings.
  • The repository went up under the Apache 2.0 license on September 18th, one day after the team's paper appeared in Science, and it includes training and inference code, preprocessing tools and pretrained checkpoints.
  • Training used 424,911 contrast-enhanced abdominal CT examinations and more than 15 million anatomy-aware image-text pairs, with supervision taken from the clinical reports attached to the scans.
  • Across evaluations covering nearly 40,000 real-world examinations, the study reported a mean area under the curve of 0.913 over the 146 findings.
  • Radiologists working with the model improved sensitivity by about 10% and cut reading time by more than 30%, according to the paper.

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Why it matters

  • capability A team wanting 146-finding abdominal coverage had to assemble hand-labeled sets one disease at a time; an inspectable checkpoint with preprocessing code removes that build step for anyone willing to validate it locally.
  • decision Anyone evaluating the checkpoint has to check their own scanner protocols and reporting vocabulary before trusting the published means, because the labels came from one network's radiology reports.
  • contradiction A product scoped on the cancer-detection framing would promise something the study did not test; the 146 are radiological findings, and cancers are a subset of them.
  • constraint The strongest clinical evidence in the paper is an assisted-reading result, which holds the near-term deployment at second reader with a physician still signing the report.

Report supervision is what makes the breadth affordable. RADAR splits a CT volume into anatomical regions and associates each region with the descriptions of it in the radiology report [10]. Across the training set that comes to more than 35 anatomy-aware image-text pairs per examination [21]. No clinician had to draw or label every example by hand, disease by disease [9]. Jianpeng Zhang, the senior algorithm researcher at DAMO Academy on the team, works on medical-image analysis, multimodal learning and vision-language pretraining [19].

The supervision is therefore whatever the reporting radiologists wrote. For the reported numbers to transfer, a hospital's scans have to be contrast-enhanced, because that is what the model reads [2], and its reporting vocabulary has to carve the abdomen up roughly the way the training reports did. Runtimewire's report says patient populations, scanners, reporting standards and disease prevalence in routine workflows can all shift the balance between missed findings and false alarms [18].

AUC measures how reliably a model separates positive from negative cases across thresholds, and it is not the percentage of patients diagnosed correctly [12]. A deployment picks thresholds, one per finding, and a mean over 146 findings does not say where any of them should go.

An AAAS summary of the study reports 0.895 across cohorts from eight external medical centers and 0.904 across more than 27,000 emergency CT cases [14]. Those sit 0.018 and 0.009 below the study's overall mean [23]. The same summary puts the best competing vision-language model in the researchers' evaluation at 0.776, which is 0.137 below RADAR [13][24].

The Science paper reports RADAR's average accuracy above that of 23 of the 26 radiologists it was compared against, drawn from multiple hospitals [15]. Three were at or above it [22]. The report says that comparison supports a second-reader or worklist role, and does not establish that the model can operate independently or improve patient outcomes [26].

The count in circulation needs care. The South China Morning Post described the model as detecting cancer and nearly 150 conditions [5]. The study evaluates 146 radiological findings, a category that includes cancers alongside other diseases and abnormalities [6], and runtimewire's report calls RADAR a broad abdominal imaging model, not a detector for 146 different cancers [7].

The repository is Apache 2.0 [3], which settles reuse and nothing about clearance. The team's phrase for RADAR, the world's first "expert-level generalist medical imaging model", is its own characterization and not a regulatory designation [17]. The same report says the breadth could shorten development cycles while regulation and prospective clinical evidence remain the gatekeepers [25].

What to watch

  • Prospective studies in routine hospital workflows reporting per-finding sensitivity and false-alarm rates instead of a mean AUC across 146 findings.
  • Whether any regulator clears a device derived from the released checkpoints, since the Apache 2.0 license settles reuse and not clearance.
  • Whether independent groups reproduce the reported AUCs on cohorts outside the eight external centers named in the study.
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