Early Fusion of Texture-Encoded CT with CXR Images for Pulmonary Disease Classification
摘要
The COVID-19 pandemic has highlighted the need for reliable and fast diagnostic systems that go beyond the limitations of RT-PCR and single-image analysis. This study introduces a Texture-Encoded Early Fusion Model that combines Computed Tomography (CT) and Chest X-ray (CXR) images at the input stage. Unlike most existing multimodal approaches that rely on feature-level or late-fusion strategies, the proposed method performs channel-level early fusion by stacking handcrafted CT texture representations with CXR images before convolutional feature learning, enabling early cross-modal interaction while preserving modality-specific characteristics. Texture descriptors, including the Discrete Wavelet Transform (DWT), Gabor Filtering, Histogram of Oriented Gradients (HOG), Gray-Level Co-occurrence Matrix (GLCM), and Local Binary Patterns (LBP), are integrated with a pretrained VGG19 backbone to extract combined spatial and texture features. This early fusion strategy enhances sensitivity to disease-specific patterns such as ground-glass opacities and lung consolidations. A structured augmentation strategy is employed to address class imbalance and handle unpaired CT and CXR data. The proposed framework is evaluated on binary, 3-class, and 4-class COVID-19 classification tasks, achieving accuracies of 96.84%, 95.73%, and 94.13%, respectively, and consistently outperforming single-modality baselines.
Ablation studies confirm that each texture descriptor contributes to performance improvement, with wavelet-based fusion yielding the strongest results. Further analysis of fusion operators shows that learnable mechanisms, such as 1