Machine learning-based method for the detection of dextrocardia in ultrasound video clips

Dextrocardia is a congenital anomaly arising during fetal development, characterised by the abnormal positioning of the heart on the right side of the chest, instead of its usual anatomical location on the left. This paper describes a machine learning-based method to automatically assess ultrasound (US) transverse videos to detect dextrocardia by analysing the Situs and four-chamber (4CH) views.

The method processes ultrasound video sweeps that users capture, which include the Situs and 4CH views. The automated analysis method consists of three stages. First, four fetal anatomical structures (chest, spine, stomach and heart) are automatically segmented using SegFormer. Second, a quality assessment (QA) module verifies that the video includes informative frames. Thirdly, the orientation of the stomach and heart relative to the fetal chest (either right or left side) is determined to assess dextrocardia. The method utilises a Transformer-based segmentation model to perform segmentation of the fetal anatomy. Segmentation performance was evaluated using the Dice coefficient, and fetal anatomy centroid estimation accuracy using root mean squared error (RMSE). Dextrocardia was classified based on a frame-based classification score (FBCS). The datasets consist of 142 pairs of Situs and 4CH US (284 frames in total) for training; and 14 US videos (7 normal, 7 dextrocardia, 2,916 frames total) for testing.

The method achieved a Dice score of 0.968, 0.958, 0.953, 0.949 for chest, spine, stomach and heart segmentation, respectively, and anatomy centroid RMSE of 0.23mm, 0.34mm, 0.25mm, 0.39mm for the same structures. The QA rejected 172 frames. The assessment for dextrocardia achieved a FBCS of 0.99 with a standard deviation of 0.01 for normal and 0.02 for dextrocardia videos.

Our automated method demonstrates accurate segmentation and reliable detection of dextrocardia from US videos. Due to the simple acquisition protocol and its robust analytical pipeline, our method is suitable for healthcare providers who are non-cardiac experts. It has the potential to facilitate earlier and more consistent prenatal identification of dextrocardia during screening, particularly in settings with limited access to experts in fetal echocardiography.