Painchaud, Nathan
Fusing Echocardiography Images and Medical Records for Continuous Patient Stratification
Painchaud, Nathan, Courand, Pierre-Yves, Jodoin, Pierre-Marc, Duchateau, Nicolas, Bernard, Olivier
Deep learning now enables automatic and robust extraction of cardiac function descriptors from echocardiographic sequences, such as ejection fraction or strain. These descriptors provide fine-grained information that physicians consider, in conjunction with more global variables from the clinical record, to assess patients' condition. Drawing on novel transformer models applied to tabular data (e.g., variables from electronic health records), we propose a method that considers all descriptors extracted from medical records and echocardiograms to learn the representation of a difficult-to-characterize cardiovascular pathology, namely hypertension. Our method first projects each variable into its own representation space using modality-specific approaches. These standardized representations of multimodal data are then fed to a transformer encoder, which learns to merge them into a comprehensive representation of the patient through a pretext task of predicting a clinical rating. This pretext task is formulated as an ordinal classification to enforce a pathological continuum in the representation space. We observe the major trends along this continuum for a cohort of 239 hypertensive patients to describe, with unprecedented gradation, the effect of hypertension on a number of cardiac function descriptors. Our analysis shows that i) pretrained weights from a foundation model allow to reach good performance (83% accuracy) even with limited data (less than 200 training samples), ii) trends across the population are reproducible between trainings, and iii) for descriptors whose interactions with hypertension are well documented, patterns are consistent with prior physiological knowledge.
Extraction of volumetric indices from echocardiography: which deep learning solution for clinical use?
Ling, Hang Jung, Painchaud, Nathan, Courand, Pierre-Yves, Jodoin, Pierre-Marc, Garcia, Damien, Bernard, Olivier
Deep learning-based methods have spearheaded the automatic analysis of echocardiographic images, taking advantage of the publication of multiple open access datasets annotated by experts (CAMUS being one of the largest public databases). However, these models are still considered unreliable by clinicians due to unresolved issues concerning i) the temporal consistency of their predictions, and ii) their ability to generalize across datasets. In this context, we propose a comprehensive comparison between the current best performing methods in medical/echocardiographic image segmentation, with a particular focus on temporal consistency and cross-dataset aspects. We introduce a new private dataset, named CARDINAL, of apical two-chamber and apical four-chamber sequences, with reference segmentation over the full cardiac cycle. We show that the proposed 3D nnU-Net outperforms alternative 2D and recurrent segmentation methods. We also report that the best models trained on CARDINAL, when tested on CAMUS without any fine-tuning, still manage to perform competitively with respect to prior methods. Overall, the experimental results suggest that with sufficient training data, 3D nnU-Net could become the first automated tool to finally meet the standards of an everyday clinical device.