REVIEW 4 major objections 5 minor 2 cited by
A multi-stage AI-plus-clinician pipeline densely labels full colonoscopy videos so modern multimodal models can be tested on real lesions, not just single-class polyps.
Reviewed by Pith at T0; open to challenge. T0 means a machine referee read the full paper against a public rubric. the ladder, T0–T4 →
T0 review · grok-4.5
2026-07-13 18:04 UTC pith:G5QUGK3M
load-bearing objection Useful multi-task colonoscopy video benchmark with a practical agentic labeling recipe; multi-class quality is only partially grounded, but the release and evaluations still move the field. the 4 major comments →
Colon-Bench: An Agentic Workflow for Scalable Dense Lesion Annotation in Full-Procedure Colonoscopy Videos
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
A multi-stage agentic annotation pipeline that successively filters VLM proposals through verification, EdgeTAM tracking, cued AI confirmation, and clinician review yields a verified multi-task colonoscopy benchmark of 528 windows, 14 lesion categories, over 300k boxes, 213k masks and 133k clinical words; on that benchmark modern multimodal models achieve strong localization (up to 48.3 mIoU) and a distilled colon-skill prompt improves zero-shot VQA by up to 9.7 percent.
What carries the argument
The multi-stage agentic workflow (temporal VLM proposals → verification agent → EdgeTAM box/mask tracking → cued AI confirmation → human-in-the-loop clinician review) that both densifies labels and progressively raises precision on the retained windows.
Load-bearing premise
That successive Gemini-based filters plus an 11.6 percent final human rejection rate produce high-quality labels for all fourteen lesion types, even though the quantitative precision/recall gains are measured only against the surrogate polyp boxes of the source dataset.
What would settle it
An independent multi-class re-annotation of a random subset of the 528 windows by clinicians who never saw the AI proposals; if their agreement with the released boxes, masks and clinical text falls well below the reported 88.4 percent acceptance rate, the quality claim fails.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper introduces Colon-Bench, a multi-task colonoscopy video benchmark produced by a multi-stage agentic annotation pipeline applied to REAL-COLON full-procedure videos. The pipeline combines VLM temporal proposals, verification filtering, EdgeTAM tracking, cued AI confirmation, and clinician review to yield 528 curated windows spanning 14 lesion categories, ~300k bounding boxes, ~213k masks, and ~133k words of clinical text. The authors use this resource to evaluate modern MLLMs on binary lesion classification, open-vocabulary video object segmentation (via three MLLM boxes prompting EdgeTAM), and prompted/unprompted video VQA, reporting strong Gemini-class localization (up to 48.3 mIoU) relative to SAM-3 and a distilled “colon-skill” prompt that improves zero-shot VQA by up to 9.7%. Stage-wise ablations against REAL-COLON polyp boxes, human acceptance rates, VQA debiasing, and frame-count/temporal-context ablations are provided.
Significance. If the multi-class dense labels are as reliable as claimed, Colon-Bench would fill a genuine gap: existing public colonoscopy resources are largely single-class polyp sets or anatomy-focused, and lack the joint spatial–temporal–linguistic supervision needed for modern MLLM evaluation. The agentic pipeline, public code/dataset link, multi-task suite (classification, OV-VOS, two-tier VQA), careful polyp-surrogate stage ablations (Tables 2 and 7), VQA debiasing protocol, and training-free colon-skill gains are concrete contributions that would be useful to the medical video and MLLM communities. The work is therefore significant as a resource paper, provided multi-class label quality and circularity risks are more rigorously bounded.
major comments (4)
- [§2.1, Tables 2 and 7] §2.1 and Tables 2/7: Stage-wise precision/recall/F1/specificity gains are computed exclusively against REAL-COLON polyp bounding boxes. Non-polyp classes that define the claimed 14-category taxonomy (ulcers, bleeding, SSL, angioectasia, diverticulum, etc.; Fig. 2) have no independent frame-level spatial or temporal ground truth. Because the central claim is a verified multi-class dense benchmark, the manuscript needs either (i) a clinician-annotated multi-class subsample with per-class spatial metrics or (ii) an explicit, quantified limitation that only polyp localization is externally validated.
- [§2.1, Table 3, §3.1] §2.1 and Table 3: Annotation proposals, verification, confirmation, and VQA item generation all rely on Gemini-family models that later dominate the leaderboard (Gemini 3 Pro/Flash top VQA and segmentation). Human review rejects only 11.6% of the final 597 windows and is described as binary accept/reject of pre-rendered overlay clips, not exhaustive multi-label spatial/temporal re-annotation. Residual systematic Gemini biases on non-polyp morphology can therefore propagate into both the benchmark and the reported rankings (including 48.3 mIoU and +9.7% colon-skill). The paper should report inter-rater or independent-clinician agreement on a stratified multi-class subset and, where possible, re-run key leaderboard entries with non-Gemini annotation sources or held-out human labels.
- [§2.2, Fig. 4, Table 3] §2.2 Baselines and Fig. 4: The OV-VOS protocol evaluates MLLMs by eliciting three boxes that seed EdgeTAM, then reporting tracker IoU/Dice. This is a fair localization-plus-propagation proxy, but it is not pure open-vocabulary video segmentation by the MLLM itself; SAM-3 is compared under a different regime. The manuscript should state this protocol limitation more prominently in the main results and avoid language that equates the numbers with end-to-end MLLM video segmentation.
- [§2.2 Debiasing Colon-Bench] §2.2 Debiasing: Blind text-only accuracy remains 44.6% (prompted) and 37.1% (unprompted) vs. 20% chance after two-stage adversarial distractor regeneration. Residual margins are attributed to dataset priors, but the paper does not quantify how much of the MLLM gains (especially colon-skill) could still exploit those priors rather than visual evidence. A short control that reports accuracy under scrambled or frozen video (or text-only with skill) would strengthen the claim that improvements reflect colonoscopy visual reasoning.
minor comments (5)
- [Global] Throughout: Multiple typos and inconsistencies (e.g., “Colon-becnh”, “segemtnation”, “evluated”, “Modles”, “Visual Quesion Answering”, “Title Suppressed Due to Excessive Length” headers). A full copy-edit pass is needed.
- [Table 1, §2.2] Table 1 vs. abstract/body: Frame and video counts should be cross-checked for consistency (464,035 frames / 528 videos in the curated set vs. the broader 1,597-clip evaluation suite in §2.2).
- [Fig. 3, Figs. 9–10] Fig. 3 and qualitative figures: Some rows mix detection and segmentation; captions should state which task and whether overlays are model boxes or EdgeTAM masks.
- [License / Acknowledgments] License/ethics: The CC BY note and REAL-COLON copyright retention are good; briefly state IRB/consent status of the source videos and any de-identification steps for clinical text.
- [§3.1, Fig. 16] §3.1 colon-skill: The skill text (Fig. 16) is useful; clarify whether it was frozen before the final re-evaluation or tuned on the same error set used for reporting, to avoid train–test leakage of the skill itself.
Circularity Check
Minor evaluation contamination in colon-skill (distilled from full-benchmark errors, then re-scored on the same set); the core annotation and MLLM claims are not circular by construction.
specific steps
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fitted input called prediction
[§3.1 Colon-Skill for MLLMs; also Appendix C.2 / Table 18 / Fig. 5]
"First, we collect per-model VQA predictions on the full benchmark and stratify errors by lesion category (Fig. 2), retaining only questions that a majority of models answer incorrectly. These shared failure cases, along with their question/answer context and category metadata, are fed to a frontier large language model which synthesises a concise, natural-language Colon-Skill... Second, we prepend this Colon-Skill to every VQA prompt and re-evaluate all models under identical conditions, yielding consistent improvements up to +9.7% (Fig. 5)."
The skill text is fitted to majority-error items from the full prompted/unprompted VQA sets, then the same sets are re-scored with that skill prepended. Reported gains (up to +9.7 pp) are therefore measured on the data used to construct the intervention, not on held-out questions. This is evaluation contamination of a secondary claim, not a forced mathematical identity; some models still drop (e.g. Molmo), so the result is not fully by-construction, but the improvement is not an independent out-of-sample prediction.
full rationale
Colon-Bench is an empirical dataset/benchmark paper, not a first-principles derivation. The agentic annotation chain (VLM proposals → verification → EdgeTAM tracking → cued AI confirmation → clinician review) is validated against external REAL-COLON polyp boxes (Table 2, Table 7) and a final human accept/reject gate (69/597 rejected). Those steps do not reduce to self-definition or a self-citation uniqueness theorem. MLLM leaderboard results are zero-shot evaluations on held-out model weights, not fitted parameters renamed as predictions. The only clear circularity-adjacent step is colon-skill: error patterns are collected on the full VQA benchmark, synthesized into a skill prompt, and re-evaluated on that same benchmark, so the reported +9.7% is not a held-out generalization claim. That is mild fitted-input contamination of one secondary result, not a load-bearing reduction of the paper’s main contribution. No self-citation uniqueness chain, ansatz smuggling, or self-definitional equations appear. Score 2 reflects one minor non-load-bearing evaluation circularity; the dataset construction and primary MLLM comparisons remain independently grounded.
Axiom & Free-Parameter Ledger
free parameters (2)
- number of detection frames per window for segmentation =
3
- retention thresholds of successive AI filters
axioms (4)
- domain assumption REAL-COLON polyp bounding boxes constitute a valid surrogate for measuring temporal precision/recall of the multi-lesion pipeline.
- domain assumption A single experienced surgeon’s binary accept/reject on short overlaid clips is sufficient final quality control for free-text clinical descriptions and multi-label categories.
- ad hoc to paper EdgeTAM tracker seeded by three MLLM boxes fairly measures open-vocabulary video object segmentation performance of the MLLM.
- ad hoc to paper Two-stage adversarial distractor regeneration plus blind text-only stress test adequately removes surface-form shortcuts from Gemini-generated VQA items.
invented entities (2)
-
Colon-Bench multi-task suite (prompted/unprompted VQA, binary classification, OV-VOS)
independent evidence
-
colon-skill prompting strategy
no independent evidence
read the original abstract
Early screening via colonoscopy is critical for colon cancer prevention, yet developing robust AI systems for this domain is hindered by the lack of densely annotated, long-sequence video datasets. Existing datasets predominantly focus on single-class polyp detection and lack the rich spatial, temporal, and linguistic annotations required to evaluate modern Multimodal Large Language Models (MLLMs). To address this critical gap, we introduce Colon-Bench, generated via a novel multi-stage agentic workflow. Our pipeline seamlessly integrates temporal proposals, bounding-box tracking, AI-driven visual confirmation, and human-in-the-loop review to scalably annotate full-procedure videos. The resulting verified benchmark is unprecedented in scope, encompassing 528 videos, 14 distinct lesion categories (including polyps, ulcers, and bleeding), over 300,000 bounding boxes, 213,000 segmentation masks, and 133,000 words of clinical descriptions. We utilize Colon-Bench to rigorously evaluate state-of-the-art MLLMs across lesion classification, Open-Vocabulary Video Object Segmentation (OV-VOS), and video Visual Question Answering (VQA). The MLLM results demonstrate surprisingly high localization performance in medical domains compared to SAM-3. Finally, we analyze common VQA errors from MLLMs to introduce a novel "colon-skill" prompting strategy, improving zero-shot MLLM performance by up to 9.7% across most MLLMs. The dataset and the code are available at https://abdullahamdi.com/colon-bench .
Forward citations
Cited by 2 Pith papers
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**Assess the geometry:** Is it a mass (protruding), a defect (depressed/ulcerated), a hole (diverticulum), or a flat vascular anomaly?
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[30]
**Evaluate the attachment:** If it’s a polyp, is it draped over/broadly attached to a fold (sessile) or hanging by a tether (pedunculated)?
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**Check the lighting mode:** Is the image under white light (pink/red hues) or NBI/BLI (green/brown/cyan hues)? Adjust color descriptions accordingly
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**Examine the surface & margins:** Is the surface smooth, cloud-like, granular, or lobulated? Are the margins sharp, rolled, or indistinct?
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Colon-Skill Prompt Context.The colon-skillSKILL.mdfile is used as context augmentation for MLLMs in the VQA benchmarks
**Identify active tools or residue:** Are there white/yellow strings (mucus/stool), active red oozing (bleeding), a wire loop (snare), or blue fluid (submucosal injection)? Fig.16. Colon-Skill Prompt Context.The colon-skillSKILL.mdfile is used as context augmentation for MLLMs in the VQA benchmarks. The skill is extracted by analysing error patterns acros...
discussion (0)
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