The integration of laboratory tests and medical images is crucial in making accurate disease prediction. However, imaging data exhibits temporal sparsity, compared to frequently collected laboratory tests. This temporal sparsity limits effective multi-modal interaction, which in turn degrades the prediction accuracy. We address this issue by generating additional medical images at more time points, conditioned on the laboratory tests. Inspired by the pivotal role of organs in mediating laboratory tests and imaging abnormalities, we propose an Organ-Centric Modal-Shared Image Generator. It converts laboratory tests into imaging abnormalities through two key components: 1) Organ-Centric Graph: It positions organs as central nodes connecting laboratory tests and imaging abnormalities; and 2) Knowledge-Guided Modal-Shared Trajectory Module: It binds multi-modal features across time into a unified organ state trajectory. Experimental results demonstrate that our method improves multi-modal prediction performance across various diseases. Code is available at https://github.com/LyapunovStability/Lab_Guide_Med_Image _Gen.

Mortality prediction is necessary for patients in the Intensive Care Unit (ICU). Clinical time series provide essential insights for making accurate predictions. However, existing prediction models often struggle with domain shifts when applied across different domains. Privacy concern hinders model calibration due to the forbidden data sharing across domains. Test-Time Training (TTT) has been increasingly researched to tackle the above issues by updating a source model to each single target sample before inference. While massive vision-based TTT methods are proposed, deploying TTT in clinical time series still faces the unique challenge of temporal imbalance: Time points tend to cluster around specific periods in some patients. Neglecting the temporal imbalance in TTT can make the model biased toward dense local pattern, resulting in unsatisfactory prediction. To overcome this challenge, we propose a novel Test-Time Training method with Diversified Local Aggregation Consistency (DLAC-TTT). During the test-time update, DLAC-TTT focuses on the distinct temporal distributions within each patient, enforcing their local diversity and global consistency through aggregation. In this way, it can mitigate the over-reliance on specific local patterns and well integrate diverse local patterns for global learning. Extensive experiments show that DLAC-TTT can boost the generalization performance across real-world clinical datasets from different medical institutes.

The real-world Electronic Health Records (EHRs) present irregularities due to changes in the patient's health status, resulting in various time intervals between observations and different physiological variables examined at each observation point. There have been recent applications of Transformer-based models in the field of irregular time series. However, the full attention mechanism in Transformer overly focuses on distant information, ignoring the short-term correlations of the condition. Thereby, the model is not able to capture localized changes or short-term fluctuations in patients' conditions. Therefore, we propose a novel end-to-end Deformable Neighborhood Attention Transformer (DNA-T) for irregular medical time series. The DNA-T captures local features by dynamically adjusting the receptive field of attention and aggregating relevant deformable neighborhoods in irregular time series. Specifically, we design a Deformable Neighborhood Attention (DNA) module that enables the network to attend to relevant neighborhoods by drifting the receiving field of neighborhood attention. The DNA enhances the model's sensitivity to local information and representation of local features, thereby capturing the correlation of localized changes in patients' conditions. We conduct extensive experiments to validate the effectiveness of DNA-T, outperforming existing state-of-the-art methods in predicting the mortality risk of patients. Moreover, we visualize an example to validate the effectiveness of the proposed DNA.

Medical time series have been widely employed for disease prediction. Missing data hinders accurate prediction. While existing imputation methods partially solve the problem, there are two challenges for medical time series: (1) High dimensionality: Existing imputation methods existing methods suffer from the trade-off between accuracy and computational efficiency. (2) Irregularity: Medical time series exhibit the dynamic temporal relationship that changes over varying sampling densities. However, existing methods mainly take the stationary mechanism, which struggles with capturing the dynamic temporal relationships. To overcome the above deficiencies, we propose a Density-Aware Temporal Attentive Step-wise Diffusion Model (DA-TASWDM), which imputes each time step based on a non-iterative diffusion model and captures inter-step dependency with the density-aware time similarity. Specifically, DA-TASWDM exploits two novel modules: (1) Density-Aware Temporal Attention (DA-TA): It correlates inter-step values from the time embedding similarity adjusted with varying sampling densities. (2) Non-Iterative Step-wise Diffusion Imputer (NI-SWDI): It directly recovers the missing values at each time step from noise without diffusion iteration. Compared with the existing methods, DA-TASWDM can achieve promising accuracy without sacrificing computational efficiency. Extensive experimental results on three real-world datasets demonstrate that our method can significantly outperform state-of-the-art methods in both imputation and post-imputation performance.