Multi-Resolution Attention-Fused, Calibration-Aware Diagnosis of Kidney CT (Normal/Cyst/Stone/Tumour)

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Author(s)

Shanker M. C. 1 N. Sankar Ram 2 V. Gokula Krishnan 3,* Pinagadi Venkateswararao 4 Therasa Michael 5 S. Kaviarasan 6

1. Department of Biomedical Engineering, VelTech MultiTech Dr. Rangarajan Dr. Sakunthala Engineering College, Chennai, Tamil Nadu, India

2. Department of CSE-AIML, SRM Institute of Science and Technology, Ramapuram, Chennai, Tamil Nadu, India

3. Department of Computer Science and Engineering, Easwari Engineering College, Chennai, Tamil Nadu, India

4. Department of CSE, CVR College of Engineering, Hyderabad, Telangana, India

5. Department of CSE, Panimalar Engineering College, Chennai, Tamil Nadu, India

6. Department of CSE, Vel Tech Rangarajan Dr Sagunthala R&D Institute of Science and Technology, Avadi, Tamil Nadu, India

* Corresponding author.

DOI: https://doi.org/10.5815/ijem.2026.05.14

Received: 11 Jun. 2026 / Revised: 24 Jun. 2026 / Accepted: 2 Jul. 2026 / Published: 8 Oct. 2026

Index Terms

Computed tomography, Multi-class Brier term, Tiny high-contrast targets, Calibration-aware objective, Class-balanced sampling, Normalization

Abstract

Accurate classification of kidney abnormalities from computed tomography (CT) images is essential for early diagnosis and clinical decision-making. However, distinguishing kidney stones, cysts, tumours, and normal kidneys remains challenging because of variations in lesion size, appearance, and imaging conditions. This study proposes a multi-resolution attention-fused, calibration-aware deep learning framework for four-class kidney CT image classification. The framework integrates convolutional neural networks and a Vision Transformer to extract complementary local and global features, which are combined through an adaptive attention-based fusion mechanism. Calibration-aware learning, incorporating focal loss, multi-class Brier loss, and feature-level orthogonality regularization, is employed to improve prediction reliability and confidence estimation. The model was trained and evaluated using an image-level data split on a publicly available kidney CT dataset containing normal, cyst, stone, and tumour images. Experimental results demonstrate an overall classification accuracy of 99.3%, a Macro-F1 score of 99.1%, an AUROC of 0.999, and an AUPRC of 0.998 on the independent test set. Robustness analysis under synthetic image corruptions showed only a modest reduction in performance, with the AUROC remaining at 0.995 under severe motion blur conditions. External validation on two independent cohorts (External Site-A and External Site-B) achieved AUROC values of 0.993 and 0.988, respectively, while post-hoc temperature scaling improved calibration by reducing the Expected Calibration Error (ECE) from 0.028 to 0.012 and 0.034 to 0.015. These results demonstrate that the proposed framework provides accurate, robust, and well-calibrated predictions, supporting its potential application in computer-aided kidney CT image analysis.

Cite This Paper

Shanker M. C., N. Sankar Ram, V. Gokula Krishnan, Pinagadi Venkateswararao, Therasa Michael, S. Kaviarasan, "Multi-Resolution Attention-Fused, Calibration-Aware Diagnosis of Kidney CT (Normal/Cyst/Stone/Tumour)", International Journal of Engineering and Manufacturing (IJEM), Vol.16, No.5, pp. 255-271, 2026. DOI:10.5815/ijem.2026.05.14

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