Validation of an Artificial Intelligence Algorithm Identifying Echocardiographic Reference Views. Ultrasound - Cardiac Acquisition Guide

In response to this problem, several teams have taken advantage of advances in deep learning, particularly in the field of computer vision, to help non-specialists obtain these reference views. Using convolutional neural networks, several teams have developed algorithms for identifying and distinguishing these views. The objective of this work is to provide assistance to the operator by identifying in real time the ultrasound image obtained as a reference view.

Since January 2019, the echocardiography laboratory headed by Prof. Stéphane Lafitte and DESKi, a Bordeaux-based start-up specialising in deep learning and medical imaging, have been working on this type of solution. In particular, they were able to develop an algorithm based on retrospective data that classifies images according to 7 reference views (parasternal long axis, parasternal short axis, apical 4-3-2 cavities, sub costal 4 cavities and the inferior vena cava) and a class representing ultrasound images that do not correspond to any of these views.

The particularities of this work lie mainly in the fact that the algorithm only detects views with sufficient quality (echogenicity and visible anatomical part in the image) for a reliable analysis and that the architecture of the neural network is compatible with a real time use on a smart phone.

Independently of the teams, all these algorithms were built and validated from retrospective data, i.e. loops of ultrasound images recorded by cardiologists during standard echocardiography examinations. In these recordings, the cardiologists keep only the images corresponding to the reference views. The cardiologist then attaches each image loop or acquisition to a reference view. From these recordings labelled by the cardiologists and by a learning method, the algorithms learn to detect and distinguish these reference views. The algorithms are then validated on a sample that has not been used for training, by comparing their results with the labelling performed by the cardiologists.

The limitation of this validation is that it takes little account of the behaviour of the algorithm when confronted with images that are not reference views.

Indeed, before recording these reference views, the operator searches for the position of the probe that offers the best view by moving it over the patient's torso. This whole scanning phase is performed during the standard examination without being recorded. None of these solutions has therefore been validated prospectively on acquisitions including the scanning phase of the reference views.

Through a prospective monocentric study, the objective of the research is to compare the labelling carried out by the algorithm and that carried out by cardiologists from acquisitions including the recording of the reference view search phase and obtained as part of routine care in the echocardiography laboratory.

Inclusion criteria

• Patients (male or female) over 18 years of age,
• Patient having an echocardiography examination scheduled at the echocardiography laboratory of the Bordeaux University Hospital,
• Patient having given his non-opposition to participate in the research (at the latest on the day of inclusion and before any examination required by the research),
• Subjects affiliated to or benefiting from a social security scheme,
• Women of childbearing age benefiting from effective contraception.

Exclusion criteria

• Person subject to a legal protection measure (safeguard of justice, guardianship or curators),
• Person deprived of liberty by judicial or administrative decision,
• Person who is unable to give his/her non-opposition,
• Pregnant or breastfeeding women.