REVIEW 5 major objections 4 minor 35 references
KM-UNet KAN Mamba UNet for medical image segmentation
T0 review · 5 major / 4 minor · reviewed 2026-08-10 · deepseek-v4-flash
Pith's one-line read KM-UNet claims that fusing KAN layers with Mamba-style selective scanning in a U-Net beats established U-Net variants on five medical segmentation benchmarks while staying small and fast.
desk verdict Plausible incremental architecture with promising efficiency numbers, but the empirical claims currently outrun the experimental reporting. read the letter →
The pith
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
The reading
What carries the argument
The load-bearing mechanism is the SEM (Selective-Scan Efficient Multi-scale) attention module paired with tokenized KAN blocks. SEM unfolds the feature map into sequences along four scan directions, passes each through an Mamba-derived S6 block, merges them back, then runs multi-scale attention through parallel 1×1 and 3×3 convolutions. The Tok-KAN phase replaces MLP linear transforms with learnable activation functions based on the Kolmogorov-Arnold representation theorem, using a residual connection of the form $Z' = \text{LN}(Z + \text{DwConv}(\Phi(Z)))$. This carries the argument because the four-direction selective scan supplies long-range dependency, while KAN supplies parameter-efficient nonlinear feature representation and the claimed interpretability.
What would settle it
Retrain U-Net, Att-UNet, UNet++, U-NeXt, Rolling-UNet, and U-Mamba using exactly KM-UNet's protocol (Adam, initial learning rate 1e-4 with cosine decay to 1e-5, batch size 8, 300 epochs, basic rotation and flipping augmentation, identical 80/20 splits) and average over at least three seeds; if the average IoU margins on ISIC17, ISIC18, CVC, BUSI, and GLAS shrink to within noise or reverse, the paper's central accuracy claim fails.
Extended reading notes
Core claim
The central claim is that KM-UNet, by replacing MLP layers in the U-Net bottleneck with tokenized KAN blocks and inserting the Selective-Scan Efficient Multi-scale (SEM) attention module in encoder and decoder, outperforms established U-Net variants (U-Net, Att-UNet, UNet++, U-NeXt, Rolling-UNet, U-Mamba) on most datasets while keeping cost low at 7.35M parameters and 17.66 Gflops. The paper also claims that the KAN layer improves explainability, with channel-activation heatmaps aligning better to ground-truth masks than without it, and that the rotation-style scanning strategy helps on single-object or simpler-shape tasks. The author frames this as the first medical-image segmentation framework integrating KANs and SSMs, providing a baseline and insights for efficient, interpretable segmentation.
Load-bearing premise
The ranking in Table 1 is taken to reflect architecture quality, but the paper reports KM-UNet's own optimizer, learning rate, batch size, augmentation, and 300-epoch schedule without stating matching protocols for the six baselines, and reports no seeds or error bars; if the baselines were trained under different conditions, the accuracy advantage could vanish.
Editorial extensions
If this is right
- If the reported numbers hold, KAN-SSM hybrids become a credible middle ground between CNNs and Transformers for medical image segmentation.
- The architecture's 7.35M parameters and 17.66 Gflops imply it could run in resource-constrained or real-time clinical settings where heavier SSM baselines such as U-Mamba (86.3M parameters, 2087 Gflops in Table 2) are impractical.
- The KAN layer's claimed interpretability, if reproducible, would give clinicians a feature-activation map that tracks target boundaries more faithfully than an MLP bottleneck.
- The rotation-from-outer-layers scanning strategy suggests a cheap accuracy lever for single-object and simple-shape segmentation tasks.
Reading between the lines
- If the reported margins are real, a natural next test is ablating the four-direction scan down to one direction on BUSI and ISIC to quantify exactly how much of the gain comes from the rotation strategy versus the KAN bottleneck.
- The same KAN-SSM design could plausibly be lifted to 3D medical segmentation, where Mamba has already shown strength and where the 17.66 Gflops budget would matter even more.
- Follow-up work will likely check whether the components are swappable — for instance, different KAN basis functions or different SSM scan orders — and whether the interpretability advantage survives outside the reported heatmaps.
Signed reviews
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper proposes KM-UNet, a U-shaped segmentation network that integrates Kolmogorov-Arnold Networks (KANs), state-space models (SSMs) via a Mamba-inspired selective-scan module, and a multi-scale attention module. The approach is evaluated on five medical segmentation benchmarks (BUSI, GlaS, CVC-ClinicDB, ISIC17, ISIC18) against six baselines, reporting an average IoU of 81.17, average F1 of 89.20, 7.35M parameters, and 17.66 Gflops. The authors claim that KM-UNet achieves the highest IoU and F1 on most datasets and strikes an excellent accuracy-efficiency balance, and that this is the first medical image segmentation framework integrating KANs and SSMs.
Significance. If the reported results are reproducible, the architecture is a potentially valuable contribution: it combines KAN-based tokenized blocks with SSM-style selective scanning in a U-Net, and the claimed efficiency (17.66 Gflops, 7.35M parameters) is attractive. The paper also provides open-source code, and the interpretability discussion is a useful direction. However, the current experimental evidence does not yet separate architectural gains from training-protocol differences, because baseline protocols, error bars, and ablation results are missing.
major comments (5)
- [Section 4, Table 1] The implementation details state that 'all results were averaged over three independent runs,' but Table 1 reports only point estimates with no standard deviations, confidence intervals, or per-run values. The margins on several datasets are small (e.g., BUSI IoU 65.42 vs. 61.81 for U-Mamba; ISIC17 IoU 84.05 vs. 82.14 for Rolling-UNet), so without variance information it is impossible to assess whether the reported ranking is statistically meaningful. Please provide error bars or per-run results for all entries.
- [Section 4, Table 1] The manuscript gives the full training protocol for KM-UNet (Adam, learning rate 1e-4 with cosine schedule, batch size 8, 300 epochs, BCE+Dice loss, random rotation and flipping) but gives no comparable protocol for the baselines U-Net, Att-UNet, UNet++, U-NeXt, Rolling-UNet, and U-Mamba. Without evidence that baselines were trained under matched data splits, augmentation, and hyperparameters, the advantage in Table 1 could reflect training choices rather than architecture quality. Please describe the baseline implementations and, ideally, retrain all methods under a common protocol.
- [Section 5, Conclusions] The conclusions state that 'ablation studies show' the SEM module improves IoU and F1 by 2%-3% and that the cosine annealing schedule outperforms a fixed learning rate, but no ablation table or corresponding experiments appear in Section 4. These claims are currently unsupported. Please include the ablation experiments with concrete numerical results, or remove the claims.
- [Section 4, Main results and Table 2] There is a substantive numerical inconsistency: the main-results text reports an average IoU of 80.45% and an average F1 of 88.63%, while Table 2 reports 81.17% and 89.20%. Please correct the discrepancy and ensure all reported numbers are consistent. Additionally, the Experiments section opens by saying 'three distinct and heterogeneous datasets' but then lists and evaluates five datasets; this should be corrected.
- [Section 3, Equations (6)-(9)] The architecture description is not sufficiently detailed for reproducibility. The channel hyperparameters C1-C5 and D1-D5 are named but not given, the KAN grid size and spline order are not specified, and Eq. (6) uses Φ(Z) without defining Φ as the composition of KAN layers from Eqs. (7)-(9). Please provide a complete specification in the text or explicitly point to the released code with the exact configuration used for the reported results.
minor comments (4)
- [Keywords] The keyword 'Manba' appears to be a typo for 'Mamba'.
- [References] Several citations appear to point to the wrong papers: [16] is cited as the source of Mamba/S6 but is 'Hungry Hungry Hippos'; [17] is cited as S4 but is U-Mamba; [20] is cited as U-NeXt but is 'White-Box Transformers via Sparse Rate Reduction'. Please recheck all references against the text.
- [Section 4, Datasets] The GlaS dataset description states it 'comprises 612 standard-definition frames derived from 31 sequences' and then says 'we used 165 images following established protocols'; this is confusing because the standard GlaS benchmark contains 165 images. Please clarify the dataset split and the source of the 612-frame count.
- [Section 4, Explainability] The explainability experiment reports qualitative heatmap comparisons and refers to changes in IoU, but it does not provide the actual IoU values or a quantitative protocol. Please report the numbers or clarify that the comparison is qualitative.
Circularity Check
No significant circularity: KM-UNet's reported results are empirical outcomes from training on public benchmarks against external baselines, not consequences of fitted constants or self-citations.
full rationale
KM-UNet's quantitative claims are produced by training the proposed architecture on five public datasets (BUSI, GlaS, CVC-ClinicDB, ISIC17, ISIC18) and comparing IoU/F1 metrics against U-Net, Att-UNet, UNet++, U-NeXt, Rolling-UNet, and U-Mamba. No equation in Sections 3-4 reduces a reported performance number to a fitted constant, to a self-authored citation, or to the claim being predicted. The KAN/SEM/S6 blocks are architectural constructions whose equations (Eqs. 1-9) define forward computations; they do not embed benchmark results. The novelty claim that KM-UNet is the first medical image segmentation framework integrating KANs and SSMs is a historical assertion about prior work, not a derivation from the benchmark outcomes. The explainability and ablation statements (e.g., 'Ablation studies show that the SEM module... with a 2%-3% increase') are not backed by an ablation table in the manuscript, and Table 1 omits matched training protocols and error bars for baselines; these are evidential and validity weaknesses that could change rankings under fair re-runs, but they are not circular. The paper does not rely on a self-citation chain as load-bearing support; reference [35] is related work on U-KAN and does not force the present outcome. Therefore no circular step can be exhibited; score 0.
Assumptions & free parameters
free parameters (3)
- Channel hyperparameters C1-C5 and D1-D5 =
Not reported
- KAN grid size and spline order =
Not reported
- Training hyperparameters =
Batch size 8; learning rate 1e-4 to 1e-5 cosine; 300 epochs; Adam; BCE plus Dice loss
assumptions (3)
- domain assumption Kolmogorov-Arnold representation theorem justifies replacing linear transformation matrices with learnable univariate activation functions in a U-Net without loss of representational power.
- domain assumption Four-direction selective scanning with S6 blocks provides efficient long-range, 2D spatial modeling for medical images.
- domain assumption Random 80/20 splits with basic augmentation and 300 epochs give fair, representative comparisons to published baselines.
Cite this review
Pith. "Pith review of KM-UNet KAN Mamba UNet for medical image segmentation." pith.science (2026). https://pith.science/paper/UMKIC25C
@misc{pith2026250102559,
author = {Pith},
title = {Pith review of: KM-UNet KAN Mamba UNet for medical image segmentation},
year = {2026},
howpublished = {\url{https://pith.science/paper/UMKIC25C}},
note = {Machine review of arXiv:2501.02559}
}
read the original abstract
Medical image segmentation is a critical task in medical imaging analysis. Traditional CNN-based methods struggle with modeling long-range dependencies, while Transformer-based models, despite their success, suffer from quadratic computational complexity. To address these limitations, we propose KM-UNet, a novel U-shaped network architecture that combines the strengths of Kolmogorov-Arnold Networks (KANs) and state-space models (SSMs). KM-UNet leverages the Kolmogorov-Arnold representation theorem for efficient feature representation and SSMs for scalable long-range modeling, achieving a balance between accuracy and computational efficiency. We evaluate KM-UNet on five benchmark datasets: ISIC17, ISIC18, CVC, BUSI, and GLAS. Experimental results demonstrate that KM-UNet achieves competitive performance compared to state-of-the-art methods in medical image segmentation tasks. To the best of our knowledge, KM-UNet is the first medical image segmentation framework integrating KANs and SSMs. This work provides a valuable baseline and new insights for the development of more efficient and interpretable medical image segmentation systems. The code is open source at https://github.com/2760613195/KM_UNet Keywords:KAN,Manba, state-space models,UNet, Medical image segmentation, Deep learning
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