525 research outputs found
Characterization of myocardial motion by multiple kernel learning: application to heart failure with preserved ejection fraction
International audienceThe present study aims at improving the characterization of myocardial velocities in the context of heart failure with preserved ejection fraction (HFPEF) by combining multiple descriptors. It builds upon a recent extension of manifold learning known as multiple kernel learning (MKL), which allows the combination of data of different natures towards the learning. Such learning is kept unsupervised, thus benefiting from all the inherent explanatory power of the data without being conditioned by a given class. The methodology was applied to 2D sequences from a stress echocardiography protocol from 33 subjects (21 healthy controls and 12 HFPEF subjects). Our method provides a novel way to tackle the understanding of the HFPEF syndrome, in contrast with the diagnostic issues surrounding it in the current clinical practice. Notably, our results confirm that the characterization of the myocardial functional response to stress in this syndrome is improved by the joint analysis of multiple relevant features
Image-Based Cardiac Diagnosis With Machine Learning: A Review
Cardiac imaging plays an important role in the diagnosis of cardiovascular disease (CVD). Until now, its role has been limited to visual and quantitative assessment of cardiac structure and function. However, with the advent of big data and machine learning, new opportunities are emerging to build artificial intelligence tools that will directly assist the clinician in the diagnosis of CVDs. This paper presents a thorough review of recent works in this field and provide the reader with a detailed presentation of the machine learning methods that can be further exploited to enable more automated, precise and early diagnosis of most CVDs
Deep learning cardiac motion analysis for human survival prediction
Motion analysis is used in computer vision to understand the behaviour of
moving objects in sequences of images. Optimising the interpretation of dynamic
biological systems requires accurate and precise motion tracking as well as
efficient representations of high-dimensional motion trajectories so that these
can be used for prediction tasks. Here we use image sequences of the heart,
acquired using cardiac magnetic resonance imaging, to create time-resolved
three-dimensional segmentations using a fully convolutional network trained on
anatomical shape priors. This dense motion model formed the input to a
supervised denoising autoencoder (4Dsurvival), which is a hybrid network
consisting of an autoencoder that learns a task-specific latent code
representation trained on observed outcome data, yielding a latent
representation optimised for survival prediction. To handle right-censored
survival outcomes, our network used a Cox partial likelihood loss function. In
a study of 302 patients the predictive accuracy (quantified by Harrell's
C-index) was significantly higher (p < .0001) for our model C=0.73 (95 CI:
0.68 - 0.78) than the human benchmark of C=0.59 (95 CI: 0.53 - 0.65). This
work demonstrates how a complex computer vision task using high-dimensional
medical image data can efficiently predict human survival
Explainable cardiac pathology classification on cine MRI with motion characterization by semi-supervised learning of apparent flow
We propose a method to classify cardiac pathology based on a novel approach
to extract image derived features to characterize the shape and motion of the
heart. An original semi-supervised learning procedure, which makes efficient
use of a large amount of non-segmented images and a small amount of images
segmented manually by experts, is developed to generate pixel-wise apparent
flow between two time points of a 2D+t cine MRI image sequence. Combining the
apparent flow maps and cardiac segmentation masks, we obtain a local apparent
flow corresponding to the 2D motion of myocardium and ventricular cavities.
This leads to the generation of time series of the radius and thickness of
myocardial segments to represent cardiac motion. These time series of motion
features are reliable and explainable characteristics of pathological cardiac
motion. Furthermore, they are combined with shape-related features to classify
cardiac pathologies. Using only nine feature values as input, we propose an
explainable, simple and flexible model for pathology classification. On ACDC
training set and testing set, the model achieves 95% and 94% respectively as
classification accuracy. Its performance is hence comparable to that of the
state-of-the-art. Comparison with various other models is performed to outline
some advantages of our model
HIERARCHICAL CLUSTERING TO PREDICT THE RESPONSE OF CARDIAC RESYNCHRONIZATION THERAPY IN PATIENTS WITH HEART FAILURE
The heterogeneous nature of today’s evolving health databases requires new techniques and approaches to process these data and extract clinically useful information. This relevant information obtained can be used to improve the response rate of cardiac resynchronization therapy (CRT) in patients with heart failure. Hierarchical clustering (HC) which is an unsupervised ML technique may uncover clusters within the bulk of data of patient population which is useful for strategies towards precision and personalized medicine. This study aims to investigate how HC can be used to automatically group a bulk of clinically acquired CRT data into clusters and subgroups that could confer clinically relevant information. About 165 patient data were used in the study and the analysis resulted in 4 different phenogroups with varying response rates. Some features were statistically significant when compared within the subgroups. Lastly, the study concludes that HC can be used to integrate and analyze different kinds of clinical data to aid in the identification of HF patient subgroups that are likely to respond to CRT
High-Resolution Maps of Left Atrial Displacements and Strains Estimated with 3D CINE MRI and Unsupervised Neural Networks
The functional analysis of the left atrium (LA) is important for evaluating
cardiac health and understanding diseases like atrial fibrillation. Cine MRI is
ideally placed for the detailed 3D characterisation of LA motion and
deformation, but it is lacking appropriate acquisition and analysis tools. In
this paper, we present Analysis for Left Atrial Displacements and Deformations
using unsupervIsed neural Networks, \textit{Aladdin}, to automatically and
reliably characterise regional LA deformations from high-resolution 3D Cine
MRI. The tool includes: an online few-shot segmentation network (Aladdin-S), an
online unsupervised image registration network (Aladdin-R), and a strain
calculations pipeline tailored to the LA. We create maps of LA Displacement
Vector Field (DVF) magnitude and LA principal strain values from images of 10
healthy volunteers and 8 patients with cardiovascular disease (CVD). We
additionally create an atlas of these biomarkers using the data from the
healthy volunteers. Aladdin is able to accurately track the LA wall across the
cardiac cycle and characterize its motion and deformation. The overall DVF
magnitude and principal strain values are significantly higher in the healthy
group vs CVD patients: and vs and , respectively. The time course of these metrics is
also different in the two groups, with a more marked active contraction phase
observed in the healthy cohort. Finally, utilizing the LA atlas allows us to
identify regional deviations from the population distribution that may indicate
focal tissue abnormalities. The proposed tool for the quantification of novel
regional LA deformation biomarkers should have important clinical applications.
The source code, anonymized images, generated maps and atlas are publicly
available: https://github.com/cgalaz01/aladdin_cmr_la
Deep Learning in Cardiology
The medical field is creating large amount of data that physicians are unable
to decipher and use efficiently. Moreover, rule-based expert systems are
inefficient in solving complicated medical tasks or for creating insights using
big data. Deep learning has emerged as a more accurate and effective technology
in a wide range of medical problems such as diagnosis, prediction and
intervention. Deep learning is a representation learning method that consists
of layers that transform the data non-linearly, thus, revealing hierarchical
relationships and structures. In this review we survey deep learning
application papers that use structured data, signal and imaging modalities from
cardiology. We discuss the advantages and limitations of applying deep learning
in cardiology that also apply in medicine in general, while proposing certain
directions as the most viable for clinical use.Comment: 27 pages, 2 figures, 10 table
Recent Advances in Machine Learning Applied to Ultrasound Imaging
Machine learning (ML) methods are pervading an increasing number of fields of application because of their capacity to effectively solve a wide variety of challenging problems. The employment of ML techniques in ultrasound imaging applications started several years ago but the scientific interest in this issue has increased exponentially in the last few years. The present work reviews the most recent (2019 onwards) implementations of machine learning techniques for two of the most popular ultrasound imaging fields, medical diagnostics and non-destructive evaluation. The former, which covers the major part of the review, was analyzed by classifying studies according to the human organ investigated and the methodology (e.g., detection, segmentation, and/or classification) adopted, while for the latter, some solutions to the detection/classification of material defects or particular patterns are reported. Finally, the main merits of machine learning that emerged from the study analysis are summarized and discussed. © 2022 by the authors. Licensee MDPI, Basel, Switzerland
Constrained manifold learning for the characterization of pathological deviations from normality
International audienceThis paper describes a technique to (1) learn the representation of a pathological motion pattern from a given population, and (2) compare individuals to this population. Our hypothesis is that this pattern can be modeled as a deviation from normal motion by means of non-linear embedding techniques. Each subject is represented by a 2D map of local motion abnormalities, obtained from a statistical atlas of myocardial motion built from a healthy population. The algorithm estimates a manifold from a set of patients with varying degrees of the same disease, and compares individuals to the training population using a mapping to the manifold and a distance to normality along the manifold. The approach extends recent manifold learning techniques by constraining the manifold to pass by a physiologically meaningful origin representing a normal motion pattern. Interpolation techniques using locally adjustable kernel improve the accuracy of the method. The technique is applied in the context of cardiac resynchronization therapy (CRT), focusing on a specific motion pattern of intra-ventricular dyssynchrony called septal flash (SF). We estimate the manifold from 50 CRT candidates with SF and test it on 37 CRT candidates and 21 healthy volunteers. Experiments highlight the relevance of nonlinear techniques to model a pathological pattern from the training set and compare new individuals to this pattern
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