REVIEW 3 major objections 5 minor 23 references
The uncertainty that best tracks cardiac segmentation error is not the one that most improves disease classification.
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
2026-07-14 12:21 UTC pith:U7FSKHIN
load-bearing objection Clean empirical observation that error-localization quality ≠ disease-signal quality, but the +1.7 AUROC claim is statistically fragile on N=40 with per-variant retuning. the 3 major comments →
GRC-ProbNet: Uncertainty-aware Feature Extraction for Cardiovascular Disease Classification
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
In a modular hybrid pipeline that extracts radiomic and geometric features from cardiac CT segmentations, appending structure-wise uncertainty summaries from a deep ensemble improves cardiovascular disease classification, and the uncertainty measure most correlated with segmentation error (predictive entropy) is not the one that yields the strongest classification gain (KL / epistemic disagreement).
What carries the argument
GRC-ProbNet: a five-member deep ensemble of Anatomix segmentors whose outputs are registered by a frozen Atlas-ISTN; the resulting mean probability maps yield three uncertainty maps (total entropy, Jensen-Shannon/KL epistemic, residual aleatoric) that are reduced either globally or per cardiac structure and concatenated with the original radiomic-geometric vector for an MLP classifier.
Load-bearing premise
That disagreement among five models fine-tuned on only thirteen labelled volumes yields stable, disease-informative uncertainty features that transfer to an independent forty-scan disease cohort.
What would settle it
Re-run the identical ASOCA five-fold protocol after replacing the five-member ensemble with a single deterministic Anatomix model (or with ten members) and check whether the AUROC gap between the best uncertainty-augmented variant and the deterministic baseline disappears or reverses.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper proposes GRC-ProbNet, an extension of the authors’ prior GRC-Net hybrid pipeline for CVD classification from cardiac CT. A five-member deep ensemble of fine-tuned Anatomix models produces multiple segmentations that are registered via a shared Atlas-ISTN; from the resulting probability maps the authors extract total entropy, KL/JSD (epistemic), and aleatoric uncertainty features, either as a single global scalar or as per-structure averages. These features are concatenated with the original radiomic and geometric descriptors and fed to an MLP. On MM-WHS the authors show that total entropy correlates most strongly with segmentation error (NCC 0.521), while on the 40-scan ASOCA cohort the best uncertainty-augmented variant (per-structure KL) reaches 92.92% AUROC versus a 91.25% deterministic baseline. The central scientific claim is that the uncertainty measure best aligned with segmentation error is not necessarily the one that most improves downstream disease classification.
Significance. If the comparative finding holds under tighter statistical controls, the work is a useful contribution to hybrid medical-imaging pipelines: it shows that explicit uncertainty features can carry disease-relevant signal beyond deterministic segmentations, and that error-localisation quality is an incomplete proxy for downstream utility. The systematic comparison of total/epistemic/aleatoric maps and global versus per-structure encodings is cleanly designed, the code is released, and the modular framing (uncertainty extracted before non-learned radiomic/geometric stages) is relevant to many cascaded clinical pipelines. The absolute AUROC lift is modest and currently under-powered, so the primary value lies in the methodological analysis rather than in a new state-of-the-art classifier.
major comments (3)
- Table 2: the headline claim that uncertainty features “substantially improve” AUROC (92.92% vs 91.25%) is not supported by the reported numbers. The absolute gain is +1.67 points while the standard deviations are 8.5–9.4 points; the intervals heavily overlap. No paired statistical test (e.g., Wilcoxon or permutation test across the same folds/seeds) is provided. With N=40 the observed lift is consistent with chance. The abstract, §3.3 and §4 should either supply a rigorous significance analysis or substantially temper the language of improvement.
- §3.1 and Table 2: Bayesian Optimization retunes the full MLP hyper-parameter set (L, H, p, η, E) independently for every uncertainty encoding on the same 40-scan ASOCA cohort. This confounds attribution: a 1–2-point AUROC difference can arise from the optimizer finding a better fit for a particular feature dimension rather than from a genuine disease-informative uncertainty signal. A fixed-hyperparameter ablation (or at least a shared search space with the baseline) is needed to isolate the contribution of the uncertainty features themselves.
- §2.1 and §3.1: the five Anatomix models are fine-tuned on only 13 MM-WHS volumes, and the resulting structure-wise uncertainty averages are treated as stable, transferable features on the independent ASOCA cohort. With such a small labelled set the ensemble may largely capture training-seed noise rather than anatomically meaningful epistemic disagreement. The paper should quantify ensemble diversity/stability (e.g., pairwise Dice across seeds, sensitivity of the Table 2 ranking to K) and discuss the risk that the KL advantage is an artefact of under-trained members rather than a disease-specific signal.
minor comments (5)
- Abstract: typographical error “92.92\)” (stray backslash).
- §3.1: the MM-WHS split is given as 13/1/6; with a single validation volume the early-stopping / model-selection procedure for Anatomix fine-tuning is under-specified and should be clarified.
- Table 1 reports NCC only; adding a second localisation metric (e.g., AUPRC of uncertainty vs. error voxels) would strengthen the error-correlation analysis.
- Figure 2 is informative but the multi-class vs. per-structure panels are hard to compare at print size; consider a clearer layout or an additional quantitative summary.
- §4: future work on registration-stage uncertainty is noted; a brief statement on whether the current frozen Atlas-ISTN could itself inject systematic bias into the uncertainty maps would help readers assess residual limitations.
Circularity Check
No significant circularity: the AUROC improvement is an empirical measurement on held-out ASOCA data, not forced by construction or by a load-bearing self-citation chain.
full rationale
The paper's central claims are empirical comparisons (Table 1 NCC of uncertainty maps vs. segmentation error on MM-WHS; Table 2 AUROC of uncertainty-augmented feature vectors vs. deterministic GRC-Net baseline on ASOCA 5-fold CV). Uncertainty maps are produced by a multi-seed deep ensemble of independently fine-tuned Anatomix models; the maps are then summarized into scalar or per-structure features that are simply concatenated to the existing radiomic+geometric vector and fed to an MLP. No equation equates the classification metric to the ensemble variance by definition, and no parameter is fitted on the target labels and then re-presented as a prediction of those same labels. The sole self-citation of note is the reuse of the authors' prior GRC-Net pipeline as the deterministic baseline; that baseline is an independent modular system whose radiomic/geometric features are held fixed while the new uncertainty features are ablated. Because the reported lift is measured (not derived) and the uncertainty computation does not presuppose the disease labels, the derivation chain is self-contained against external public benchmarks. Minor self-citation of the baseline does not raise the score above 1.
Axiom & Free-Parameter Ledger
free parameters (3)
- ensemble size K =
5
- MLP hyper-parameters (L, H, p, η, E) =
per-variant Optuna search
- PCA components for geometric features =
≤3
axioms (3)
- domain assumption Deep-ensemble disagreement approximates epistemic uncertainty and total entropy minus JSD isolates aleatoric uncertainty.
- domain assumption A population atlas built from 13 healthy MM-WHS volumes is a valid normative reference for both healthy and diseased ASOCA hearts.
- ad hoc to paper Structure-wise average of a voxel-wise uncertainty map is a sufficient summary statistic for downstream classification.
read the original abstract
The automatic detection and classification of cardiovascular disease (CVD) from computed tomography (CT) images plays an important role in clinical practice. Recently, a hybrid pipeline (GRC-Net) for CVD classification was proposed, which leverages a deep-learning-based segmentation and registration method to extract radiomic and geometric features. However, GRC-Net relies on a deterministic segmentation mask, without considering the inherent ambiguity associated with cardiac anatomy. In this paper, we propose GRC-ProbNet, which takes advantage of a deep ensemble to produce multiple segmentation masks for a given input. From these masks, we extract multiple uncertainty features. We analyze these uncertainty features for both their correlation with segmentation error and their propagation effects on downstream CVD classification performance. Our experiments on the publicly available MM-WHS and ASOCA datasets show that the uncertainty measure that best reflects segmentation quality is not necessarily the one that provides the strongest signal for downstream CVD classification. Overall, our results demonstrate that GRC-ProbNet utilizing uncertainty features substantially improves CVD classification AUROC (92.92\) compared to the baseline GRC-Net model (91.25%). Our code is publicly available: https://github.com/biomedia-mira/GRC-ProbNet.
Figures
Reference graph
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