Frequency-Guided Cross-Modal Interaction for Multimodal Yeast Classification Based on Light-Scattering and Microscopy Images

Accurate identification of pathogenic yeasts is essential for clinical diagnosis and effective antifungal therapy. However, current approaches predominantly rely on microscopy-based models, which require large-scale annotated datasets and exhibit limited generalization across morphologically similar species. In contrast, light-scattering (LS) imaging captures the diffraction patterns generated by internal cellular structures, providing volumetric biophysical cues that extend beyond surface morphology, yet its indirect representations pose major challenges for feature discrimination. Our objective is to develop fast and accurate methods to detect various species of yeasts. We propose FPA-YeastNet, which is a frequency-enhanced single-modality deep learning architecture that improves yeast classification in LS images by leveraging discriminative frequency-domain features. Building upon this enhanced modality, we further propose FGCA-YeastNet, a frequency-guided cross-attention network designed to integrate LS and microscopy information for complementary representation learning. The proposed multimodal model facilitates synergistic interactions between volumetric scattering structures and fine-grained cellular textures through adaptive fusion and bidirectional attention, leading to improved robustness and interpretability. Comprehensive classification experiments conducted on a multimodal yeast dataset demonstrate that FGCA-YeastNet effectively bridges the performance gap between LS and microscopy modalities, achieving significant improvements over both unimodal and multimodal baselines. The FPA-YeastNet yields an average accuracy improvement of 6.26% compared with LS-only models, and FGCA-YeastNet further provides mean gains of 19.97% and 7.67% over unimodal and multimodal baseline models, respectively. Experimental results demonstrate the diagnostic potential of light scattering and microscopic imaging and underscore the effectiveness of frequency-guided multimodal collaboration for reliable and interpretable yeast classification in clinical microbiology.